drm/i915: Reduce differences with Linux 3.8.13

[dragonfly.git] / sys / dev / drm / i915 / i915_gem.c

/*
 * Copyright © 2008 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *
 * Copyright (c) 2011 The FreeBSD Foundation
 * All rights reserved.
 *
 * This software was developed by Konstantin Belousov under sponsorship from
 * the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include <sys/resourcevar.h>
#include <sys/sfbuf.h>

#include <drm/drmP.h>
#include <drm/i915_drm.h>
#include "i915_drv.h"
#include "intel_drv.h"
#include "intel_ringbuffer.h"
#include <linux/completion.h>
#include <linux/jiffies.h>
#include <linux/time.h>

static __must_check int i915_gem_object_flush_gpu_write_domain(struct drm_i915_gem_object *obj);
static void i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj);
static void i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj);
static int i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
    unsigned alignment, bool map_and_fenceable);
static int i915_gem_phys_pwrite(struct drm_device *dev,
    struct drm_i915_gem_object *obj, uint64_t data_ptr, uint64_t offset,
    uint64_t size, struct drm_file *file_priv);

static void i915_gem_write_fence(struct drm_device *dev, int reg,
                                 struct drm_i915_gem_object *obj);
static void i915_gem_object_update_fence(struct drm_i915_gem_object *obj,
                                         struct drm_i915_fence_reg *fence,
                                         bool enable);

static uint32_t i915_gem_get_gtt_size(struct drm_device *dev, uint32_t size,
    int tiling_mode);
static uint32_t i915_gem_get_gtt_alignment(struct drm_device *dev,
    uint32_t size, int tiling_mode);
static int i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj,
    int flags);
static void i915_gem_object_finish_gtt(struct drm_i915_gem_object *obj);
static void i915_gem_object_truncate(struct drm_i915_gem_object *obj);

static inline void i915_gem_object_fence_lost(struct drm_i915_gem_object *obj)
{
        if (obj->tiling_mode)
                i915_gem_release_mmap(obj);

        /* As we do not have an associated fence register, we will force
         * a tiling change if we ever need to acquire one.
         */
        obj->fence_dirty = false;
        obj->fence_reg = I915_FENCE_REG_NONE;
}

static int i915_gem_object_is_purgeable(struct drm_i915_gem_object *obj);
static bool i915_gem_object_is_inactive(struct drm_i915_gem_object *obj);
static int i915_gem_object_needs_bit17_swizzle(struct drm_i915_gem_object *obj);
static vm_page_t i915_gem_wire_page(vm_object_t object, vm_pindex_t pindex);
static void i915_gem_process_flushing_list(struct intel_ring_buffer *ring,
    uint32_t flush_domains);
static void i915_gem_reset_fences(struct drm_device *dev);
static void i915_gem_lowmem(void *arg);

static int i915_gem_obj_io(struct drm_device *dev, uint32_t handle, uint64_t data_ptr,
    uint64_t size, uint64_t offset, enum uio_rw rw, struct drm_file *file);

MALLOC_DEFINE(DRM_I915_GEM, "i915gem", "Allocations from i915 gem");
long i915_gem_wired_pages_cnt;

/* some bookkeeping */
static void i915_gem_info_add_obj(struct drm_i915_private *dev_priv,
                                  size_t size)
{

        dev_priv->mm.object_count++;
        dev_priv->mm.object_memory += size;
}

static void i915_gem_info_remove_obj(struct drm_i915_private *dev_priv,
                                     size_t size)
{

        dev_priv->mm.object_count--;
        dev_priv->mm.object_memory -= size;
}

static int
i915_gem_wait_for_error(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct completion *x = &dev_priv->error_completion;
        int ret;

        if (!atomic_read(&dev_priv->mm.wedged))
                return 0;

        /*
         * Only wait 10 seconds for the gpu reset to complete to avoid hanging
         * userspace. If it takes that long something really bad is going on and
         * we should simply try to bail out and fail as gracefully as possible.
         */
        ret = wait_for_completion_interruptible_timeout(x, 10*hz);
        if (ret == 0) {
                DRM_ERROR("Timed out waiting for the gpu reset to complete\n");
                return -EIO;
        } else if (ret < 0) {
                return ret;
        }

        if (atomic_read(&dev_priv->mm.wedged)) {
                /* GPU is hung, bump the completion count to account for
                 * the token we just consumed so that we never hit zero and
                 * end up waiting upon a subsequent completion event that
                 * will never happen.
                 */
                spin_lock(&x->wait.lock);
                x->done++;
                spin_unlock(&x->wait.lock);
        }
        return 0;
}

int i915_mutex_lock_interruptible(struct drm_device *dev)
{
        int ret;

        ret = i915_gem_wait_for_error(dev);
        if (ret != 0)
                return (ret);

        ret = lockmgr(&dev->dev_struct_lock, LK_EXCLUSIVE|LK_SLEEPFAIL);
        if (ret)
                return -EINTR;

        WARN_ON(i915_verify_lists(dev));
        return 0;
}

static inline bool
i915_gem_object_is_inactive(struct drm_i915_gem_object *obj)
{
        return !obj->active;
}

int
i915_gem_init_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_init *args = data;

        if (drm_core_check_feature(dev, DRIVER_MODESET))
                return -ENODEV;

        if (args->gtt_start >= args->gtt_end ||
            (args->gtt_end | args->gtt_start) & (PAGE_SIZE - 1))
                return -EINVAL;

        /* GEM with user mode setting was never supported on ilk and later. */
        if (INTEL_INFO(dev)->gen >= 5)
                return -ENODEV;

        /*
         * XXXKIB. The second-time initialization should be guarded
         * against.
         */
        lockmgr(&dev->dev_lock, LK_EXCLUSIVE|LK_RETRY|LK_CANRECURSE);
        i915_gem_do_init(dev, args->gtt_start, args->gtt_end, args->gtt_end);
        lockmgr(&dev->dev_lock, LK_RELEASE);

        return 0;
}

int
i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
                            struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_get_aperture *args = data;
        struct drm_i915_gem_object *obj;
        size_t pinned;

        pinned = 0;
        DRM_LOCK(dev);
        list_for_each_entry(obj, &dev_priv->mm.gtt_list, gtt_list)
                if (obj->pin_count)
                        pinned += obj->gtt_space->size;
        DRM_UNLOCK(dev);

        args->aper_size = dev_priv->mm.gtt_total;
        args->aper_available_size = args->aper_size - pinned;

        return 0;
}

static int
i915_gem_create(struct drm_file *file, struct drm_device *dev, uint64_t size,
    uint32_t *handle_p)
{
        struct drm_i915_gem_object *obj;
        uint32_t handle;
        int ret;

        size = roundup(size, PAGE_SIZE);
        if (size == 0)
                return (-EINVAL);

        obj = i915_gem_alloc_object(dev, size);
        if (obj == NULL)
                return (-ENOMEM);

        handle = 0;
        ret = drm_gem_handle_create(file, &obj->base, &handle);
        if (ret != 0) {
                drm_gem_object_release(&obj->base);
                i915_gem_info_remove_obj(dev->dev_private, obj->base.size);
                drm_free(obj, DRM_I915_GEM);
                return (-ret);
        }

        /* drop reference from allocate - handle holds it now */
        drm_gem_object_unreference(&obj->base);
        *handle_p = handle;
        return (0);
}

int
i915_gem_dumb_create(struct drm_file *file,
                     struct drm_device *dev,
                     struct drm_mode_create_dumb *args)
{

        /* have to work out size/pitch and return them */
        args->pitch = roundup2(args->width * ((args->bpp + 7) / 8), 64);
        args->size = args->pitch * args->height;
        return (i915_gem_create(file, dev, args->size, &args->handle));
}

int i915_gem_dumb_destroy(struct drm_file *file,
                          struct drm_device *dev,
                          uint32_t handle)
{

        return (drm_gem_handle_delete(file, handle));
}

/**
 * Creates a new mm object and returns a handle to it.
 */
int
i915_gem_create_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file)
{
        struct drm_i915_gem_create *args = data;

        return (i915_gem_create(file, dev, args->size, &args->handle));
}

static int i915_gem_object_needs_bit17_swizzle(struct drm_i915_gem_object *obj)
{
        drm_i915_private_t *dev_priv;

        dev_priv = obj->base.dev->dev_private;
        return (dev_priv->mm.bit_6_swizzle_x == I915_BIT_6_SWIZZLE_9_10_17 &&
            obj->tiling_mode != I915_TILING_NONE);
}

/**
 * Reads data from the object referenced by handle.
 *
 * On error, the contents of *data are undefined.
 */
int
i915_gem_pread_ioctl(struct drm_device *dev, void *data,
                     struct drm_file *file)
{
        struct drm_i915_gem_pread *args;

        args = data;
        return (i915_gem_obj_io(dev, args->handle, args->data_ptr, args->size,
            args->offset, UIO_READ, file));
}

/**
 * Writes data to the object referenced by handle.
 *
 * On error, the contents of the buffer that were to be modified are undefined.
 */
int
i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file)
{
        struct drm_i915_gem_pwrite *args;

        args = data;
        return (i915_gem_obj_io(dev, args->handle, args->data_ptr, args->size,
            args->offset, UIO_WRITE, file));
}

int
i915_gem_check_wedge(struct drm_i915_private *dev_priv,
                     bool interruptible)
{
        if (atomic_read(&dev_priv->mm.wedged)) {
                struct completion *x = &dev_priv->error_completion;
                bool recovery_complete;

                /* Give the error handler a chance to run. */
                spin_lock(&x->wait.lock);
                recovery_complete = x->done > 0;
                spin_unlock(&x->wait.lock);

                /* Non-interruptible callers can't handle -EAGAIN, hence return
                 * -EIO unconditionally for these. */
                if (!interruptible)
                        return -EIO;

                /* Recovery complete, but still wedged means reset failure. */
                if (recovery_complete)
                        return -EIO;

                return -EAGAIN;
        }

        return 0;
}

/*
 * Compare seqno against outstanding lazy request. Emit a request if they are
 * equal.
 */
static int
i915_gem_check_olr(struct intel_ring_buffer *ring, u32 seqno)
{
        int ret;

        DRM_LOCK_ASSERT(ring->dev);

        ret = 0;
        if (seqno == ring->outstanding_lazy_request)
                ret = i915_add_request(ring, NULL, NULL);

        return ret;
}

/**
 * __wait_seqno - wait until execution of seqno has finished
 * @ring: the ring expected to report seqno
 * @seqno: duh!
 * @interruptible: do an interruptible wait (normally yes)
 * @timeout: in - how long to wait (NULL forever); out - how much time remaining
 *
 * Returns 0 if the seqno was found within the alloted time. Else returns the
 * errno with remaining time filled in timeout argument.
 */
static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno,
                        bool interruptible, struct timespec *timeout)
{
        drm_i915_private_t *dev_priv = ring->dev->dev_private;
        struct timespec before, now, wait_time={1,0};
        unsigned long timeout_jiffies;
        long end;
        bool wait_forever = true;
        int ret;

        if (i915_seqno_passed(ring->get_seqno(ring, true), seqno))
                return 0;

        if (timeout != NULL) {
                wait_time = *timeout;
                wait_forever = false;
        }

        timeout_jiffies = timespec_to_jiffies(&wait_time);

        if (WARN_ON(!ring->irq_get(ring)))
                return -ENODEV;

        /* Record current time in case interrupted by signal, or wedged * */
        getrawmonotonic(&before);

#define EXIT_COND \
        (i915_seqno_passed(ring->get_seqno(ring, false), seqno) || \
        atomic_read(&dev_priv->mm.wedged))
        do {
                if (interruptible)
                        end = wait_event_interruptible_timeout(ring->irq_queue,
                                                               EXIT_COND,
                                                               timeout_jiffies);
                else
                        end = wait_event_timeout(ring->irq_queue, EXIT_COND,
                                                 timeout_jiffies);

                ret = i915_gem_check_wedge(dev_priv, interruptible);
                if (ret)
                        end = ret;
        } while (end == 0 && wait_forever);

        getrawmonotonic(&now);

        ring->irq_put(ring);
#undef EXIT_COND

        if (timeout) {
                struct timespec sleep_time = timespec_sub(now, before);
                *timeout = timespec_sub(*timeout, sleep_time);
        }

        switch (end) {
        case -EIO:
        case -EAGAIN: /* Wedged */
        case -ERESTARTSYS: /* Signal */
                return (int)end;
        case 0: /* Timeout */
                if (timeout)
                        set_normalized_timespec(timeout, 0, 0);
                return -ETIMEDOUT;      /* -ETIME on Linux */
        default: /* Completed */
                WARN_ON(end < 0); /* We're not aware of other errors */
                return 0;
        }
}

/**
 * Waits for a sequence number to be signaled, and cleans up the
 * request and object lists appropriately for that event.
 */
int
i915_wait_seqno(struct intel_ring_buffer *ring, uint32_t seqno)
{
        drm_i915_private_t *dev_priv = ring->dev->dev_private;
        int ret = 0;

        BUG_ON(seqno == 0);

        ret = i915_gem_check_wedge(dev_priv, dev_priv->mm.interruptible);
        if (ret)
                return ret;

        ret = i915_gem_check_olr(ring, seqno);
        if (ret)
                return ret;

        ret = __wait_seqno(ring, seqno, dev_priv->mm.interruptible, NULL);

        return ret;
}

/**
 * Ensures that all rendering to the object has completed and the object is
 * safe to unbind from the GTT or access from the CPU.
 */
static __must_check int
i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
                               bool readonly)
{
        u32 seqno;
        int ret;

        if (readonly)
                seqno = obj->last_write_seqno;
        else
                seqno = obj->last_read_seqno;
        if (seqno == 0)
                return 0;

        ret = i915_wait_seqno(obj->ring, seqno);
        if (ret)
                return ret;

        /* Manually manage the write flush as we may have not yet retired
         * the buffer.
         */
        if (obj->last_write_seqno &&
            i915_seqno_passed(seqno, obj->last_write_seqno)) {
                obj->last_write_seqno = 0;
                obj->base.write_domain &= ~I915_GEM_GPU_DOMAINS;
        }

        i915_gem_retire_requests_ring(obj->ring);
        return 0;
}

/**
 * Called when user space prepares to use an object with the CPU, either
 * through the mmap ioctl's mapping or a GTT mapping.
 */
int
i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file)
{
        struct drm_i915_gem_set_domain *args = data;
        struct drm_i915_gem_object *obj;
        uint32_t read_domains = args->read_domains;
        uint32_t write_domain = args->write_domain;
        int ret;

        /* Only handle setting domains to types used by the CPU. */
        if (write_domain & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        if (read_domains & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        /* Having something in the write domain implies it's in the read
         * domain, and only that read domain.  Enforce that in the request.
         */
        if (write_domain != 0 && read_domains != write_domain)
                return -EINVAL;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (read_domains & I915_GEM_DOMAIN_GTT) {
                ret = i915_gem_object_set_to_gtt_domain(obj, write_domain != 0);

                /* Silently promote "you're not bound, there was nothing to do"
                 * to success, since the client was just asking us to
                 * make sure everything was done.
                 */
                if (ret == -EINVAL)
                        ret = 0;
        } else {
                ret = i915_gem_object_set_to_cpu_domain(obj, write_domain != 0);
        }

        drm_gem_object_unreference(&obj->base);
unlock:
        DRM_UNLOCK(dev);
        return ret;
}

/**
 * Called when user space has done writes to this buffer
 */
int
i915_gem_sw_finish_ioctl(struct drm_device *dev, void *data,
                         struct drm_file *file)
{
        struct drm_i915_gem_sw_finish *args = data;
        struct drm_i915_gem_object *obj;
        int ret = 0;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret != 0)
                return (ret);
        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Pinned buffers may be scanout, so flush the cache */
        if (obj->pin_count != 0)
                i915_gem_object_flush_cpu_write_domain(obj);

        drm_gem_object_unreference(&obj->base);
unlock:
        DRM_UNLOCK(dev);
        return (ret);
}

/**
 * Maps the contents of an object, returning the address it is mapped
 * into.
 *
 * While the mapping holds a reference on the contents of the object, it doesn't
 * imply a ref on the object itself.
 */
int
i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_mmap *args = data;
        struct drm_gem_object *obj;
        struct proc *p = curproc;
        vm_map_t map = &p->p_vmspace->vm_map;
        vm_offset_t addr;
        vm_size_t size;
        int error = 0, rv;

        obj = drm_gem_object_lookup(dev, file, args->handle);
        if (obj == NULL)
                return -ENOENT;

        if (args->size == 0)
                goto out;

        size = round_page(args->size);
        PROC_LOCK(p);
        if (map->size + size > p->p_rlimit[RLIMIT_VMEM].rlim_cur) {
                PROC_UNLOCK(p);
                error = ENOMEM;
                goto out;
        }
        PROC_UNLOCK(p);

        addr = 0;
        vm_object_hold(obj->vm_obj);
        vm_object_reference_locked(obj->vm_obj);
        vm_object_drop(obj->vm_obj);
        rv = vm_map_find(map, obj->vm_obj, args->offset, &addr, args->size,
            PAGE_SIZE, /* align */
            TRUE, /* fitit */
            VM_MAPTYPE_NORMAL, /* maptype */
            VM_PROT_READ | VM_PROT_WRITE, /* prot */
            VM_PROT_READ | VM_PROT_WRITE, /* max */
            MAP_SHARED /* cow */);
        if (rv != KERN_SUCCESS) {
                vm_object_deallocate(obj->vm_obj);
                error = -vm_mmap_to_errno(rv);
        } else {
                args->addr_ptr = (uint64_t)addr;
        }
out:
        drm_gem_object_unreference(obj);
        return (error);
}

/**
 * i915_gem_release_mmap - remove physical page mappings
 * @obj: obj in question
 *
 * Preserve the reservation of the mmapping with the DRM core code, but
 * relinquish ownership of the pages back to the system.
 *
 * It is vital that we remove the page mapping if we have mapped a tiled
 * object through the GTT and then lose the fence register due to
 * resource pressure. Similarly if the object has been moved out of the
 * aperture, than pages mapped into userspace must be revoked. Removing the
 * mapping will then trigger a page fault on the next user access, allowing
 * fixup by i915_gem_fault().
 */
void
i915_gem_release_mmap(struct drm_i915_gem_object *obj)
{
        vm_object_t devobj;
        vm_page_t m;
        int i, page_count;

        if (!obj->fault_mappable)
                return;

        devobj = cdev_pager_lookup(obj);
        if (devobj != NULL) {
                page_count = OFF_TO_IDX(obj->base.size);

                VM_OBJECT_LOCK(devobj);
                for (i = 0; i < page_count; i++) {
                        m = vm_page_lookup_busy_wait(devobj, i, TRUE, "915unm");
                        if (m == NULL)
                                continue;
                        cdev_pager_free_page(devobj, m);
                }
                VM_OBJECT_UNLOCK(devobj);
                vm_object_deallocate(devobj);
        }

        obj->fault_mappable = false;
}

static uint32_t
i915_gem_get_gtt_size(struct drm_device *dev, uint32_t size, int tiling_mode)
{
        uint32_t gtt_size;

        if (INTEL_INFO(dev)->gen >= 4 ||
            tiling_mode == I915_TILING_NONE)
                return (size);

        /* Previous chips need a power-of-two fence region when tiling */
        if (INTEL_INFO(dev)->gen == 3)
                gtt_size = 1024*1024;
        else
                gtt_size = 512*1024;

        while (gtt_size < size)
                gtt_size <<= 1;

        return (gtt_size);
}

/**
 * i915_gem_get_gtt_alignment - return required GTT alignment for an object
 * @obj: object to check
 *
 * Return the required GTT alignment for an object, taking into account
 * potential fence register mapping.
 */
static uint32_t
i915_gem_get_gtt_alignment(struct drm_device *dev,
                           uint32_t size,
                           int tiling_mode)
{

        /*
         * Minimum alignment is 4k (GTT page size), but might be greater
         * if a fence register is needed for the object.
         */
        if (INTEL_INFO(dev)->gen >= 4 ||
            tiling_mode == I915_TILING_NONE)
                return (4096);

        /*
         * Previous chips need to be aligned to the size of the smallest
         * fence register that can contain the object.
         */
        return (i915_gem_get_gtt_size(dev, size, tiling_mode));
}

/**
 * i915_gem_get_unfenced_gtt_alignment - return required GTT alignment for an
 *                                       unfenced object
 * @dev: the device
 * @size: size of the object
 * @tiling_mode: tiling mode of the object
 *
 * Return the required GTT alignment for an object, only taking into account
 * unfenced tiled surface requirements.
 */
uint32_t
i915_gem_get_unfenced_gtt_alignment(struct drm_device *dev,
                                    uint32_t size,
                                    int tiling_mode)
{

        if (tiling_mode == I915_TILING_NONE)
                return (4096);

        /*
         * Minimum alignment is 4k (GTT page size) for sane hw.
         */
        if (INTEL_INFO(dev)->gen >= 4 || IS_G33(dev))
                return (4096);

        /*
         * Previous hardware however needs to be aligned to a power-of-two
         * tile height. The simplest method for determining this is to reuse
         * the power-of-tile object size.
         */
        return (i915_gem_get_gtt_size(dev, size, tiling_mode));
}

int
i915_gem_mmap_gtt(struct drm_file *file,
                  struct drm_device *dev,
                  uint32_t handle,
                  uint64_t *offset)
{
        struct drm_i915_private *dev_priv;
        struct drm_i915_gem_object *obj;
        int ret;

        dev_priv = dev->dev_private;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret != 0)
                return (ret);

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (obj->base.size > dev_priv->mm.gtt_mappable_end) {
                ret = -E2BIG;
                goto out;
        }

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_ERROR("Attempting to mmap a purgeable buffer\n");
                ret = -EINVAL;
                goto out;
        }

        ret = drm_gem_create_mmap_offset(&obj->base);
        if (ret != 0)
                goto out;

        *offset = DRM_GEM_MAPPING_OFF(obj->base.map_list.key) |
            DRM_GEM_MAPPING_KEY;
out:
        drm_gem_object_unreference(&obj->base);
unlock:
        DRM_UNLOCK(dev);
        return (ret);
}

/**
 * i915_gem_mmap_gtt_ioctl - prepare an object for GTT mmap'ing
 * @dev: DRM device
 * @data: GTT mapping ioctl data
 * @file: GEM object info
 *
 * Simply returns the fake offset to userspace so it can mmap it.
 * The mmap call will end up in drm_gem_mmap(), which will set things
 * up so we can get faults in the handler above.
 *
 * The fault handler will take care of binding the object into the GTT
 * (since it may have been evicted to make room for something), allocating
 * a fence register, and mapping the appropriate aperture address into
 * userspace.
 */
int
i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file)
{
        struct drm_i915_private *dev_priv;
        struct drm_i915_gem_mmap_gtt *args = data;

        dev_priv = dev->dev_private;

        return (i915_gem_mmap_gtt(file, dev, args->handle, &args->offset));
}

/* Immediately discard the backing storage */
static void
i915_gem_object_truncate(struct drm_i915_gem_object *obj)
{
        vm_object_t vm_obj;

        vm_obj = obj->base.vm_obj;
        VM_OBJECT_LOCK(vm_obj);
        vm_object_page_remove(vm_obj, 0, 0, false);
        VM_OBJECT_UNLOCK(vm_obj);
        obj->madv = __I915_MADV_PURGED;
}

static inline int
i915_gem_object_is_purgeable(struct drm_i915_gem_object *obj)
{
        return obj->madv == I915_MADV_DONTNEED;
}

static inline void vm_page_reference(vm_page_t m)
{
        vm_page_flag_set(m, PG_REFERENCED);
}

static void
i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
{
        vm_page_t m;
        int page_count, i;

        BUG_ON(obj->madv == __I915_MADV_PURGED);

        if (obj->tiling_mode != I915_TILING_NONE)
                i915_gem_object_save_bit_17_swizzle(obj);
        if (obj->madv == I915_MADV_DONTNEED)
                obj->dirty = 0;
        page_count = obj->base.size / PAGE_SIZE;
        VM_OBJECT_LOCK(obj->base.vm_obj);
#if GEM_PARANOID_CHECK_GTT
        i915_gem_assert_pages_not_mapped(obj->base.dev, obj->pages, page_count);
#endif
        for (i = 0; i < page_count; i++) {
                m = obj->pages[i];
                if (obj->dirty)
                        vm_page_dirty(m);
                if (obj->madv == I915_MADV_WILLNEED)
                        vm_page_reference(m);
                vm_page_busy_wait(obj->pages[i], FALSE, "i915gem");
                vm_page_unwire(obj->pages[i], 1);
                vm_page_wakeup(obj->pages[i]);
                atomic_add_long(&i915_gem_wired_pages_cnt, -1);
        }
        VM_OBJECT_UNLOCK(obj->base.vm_obj);
        obj->dirty = 0;
        drm_free(obj->pages, DRM_I915_GEM);
        obj->pages = NULL;
}

static int
i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj,
    int flags)
{
        struct drm_device *dev;
        vm_object_t vm_obj;
        vm_page_t m;
        int page_count, i, j;

        dev = obj->base.dev;
        KASSERT(obj->pages == NULL, ("Obj already has pages"));
        page_count = obj->base.size / PAGE_SIZE;
        obj->pages = kmalloc(page_count * sizeof(vm_page_t), DRM_I915_GEM,
            M_WAITOK);
        vm_obj = obj->base.vm_obj;
        VM_OBJECT_LOCK(vm_obj);
        for (i = 0; i < page_count; i++) {
                if ((obj->pages[i] = i915_gem_wire_page(vm_obj, i)) == NULL)
                        goto failed;
        }
        VM_OBJECT_UNLOCK(vm_obj);
        if (i915_gem_object_needs_bit17_swizzle(obj))
                i915_gem_object_do_bit_17_swizzle(obj);
        return (0);

failed:
        for (j = 0; j < i; j++) {
                m = obj->pages[j];
                vm_page_busy_wait(m, FALSE, "i915gem");
                vm_page_unwire(m, 0);
                vm_page_wakeup(m);
                atomic_add_long(&i915_gem_wired_pages_cnt, -1);
        }
        VM_OBJECT_UNLOCK(vm_obj);
        drm_free(obj->pages, DRM_I915_GEM);
        obj->pages = NULL;
        return (-EIO);
}

void
i915_gem_object_move_to_active(struct drm_i915_gem_object *obj,
                               struct intel_ring_buffer *ring)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 seqno = intel_ring_get_seqno(ring);

        BUG_ON(ring == NULL);
        obj->ring = ring;

        /* Add a reference if we're newly entering the active list. */
        if (!obj->active) {
                drm_gem_object_reference(&obj->base);
                obj->active = 1;
        }

        /* Move from whatever list we were on to the tail of execution. */
        list_move_tail(&obj->mm_list, &dev_priv->mm.active_list);
        list_move_tail(&obj->ring_list, &ring->active_list);

        obj->last_read_seqno = seqno;

        if (obj->fenced_gpu_access) {
                obj->last_fenced_seqno = seqno;

                /* Bump MRU to take account of the delayed flush */
                if (obj->fence_reg != I915_FENCE_REG_NONE) {
                        struct drm_i915_fence_reg *reg;

                        reg = &dev_priv->fence_regs[obj->fence_reg];
                        list_move_tail(&reg->lru_list,
                                       &dev_priv->mm.fence_list);
                }
        }
}

static void
i915_gem_object_move_to_inactive(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;

        BUG_ON(obj->base.write_domain & ~I915_GEM_GPU_DOMAINS);
        BUG_ON(!obj->active);

        list_move_tail(&obj->mm_list, &dev_priv->mm.inactive_list);

        list_del_init(&obj->ring_list);
        obj->ring = NULL;

        obj->last_read_seqno = 0;
        obj->last_write_seqno = 0;
        obj->base.write_domain = 0;

        obj->last_fenced_seqno = 0;
        obj->fenced_gpu_access = false;

        obj->active = 0;
        drm_gem_object_unreference(&obj->base);

        WARN_ON(i915_verify_lists(dev));
}

static int
i915_gem_handle_seqno_wrap(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_ring_buffer *ring;
        int ret, i, j;

        /* The hardware uses various monotonic 32-bit counters, if we
         * detect that they will wraparound we need to idle the GPU
         * and reset those counters.
         */
        ret = 0;
        for_each_ring(ring, dev_priv, i) {
                for (j = 0; j < ARRAY_SIZE(ring->sync_seqno); j++)
                        ret |= ring->sync_seqno[j] != 0;
        }
        if (ret == 0)
                return ret;

        ret = i915_gpu_idle(dev);
        if (ret)
                return ret;

        i915_gem_retire_requests(dev);
        for_each_ring(ring, dev_priv, i) {
                for (j = 0; j < ARRAY_SIZE(ring->sync_seqno); j++)
                        ring->sync_seqno[j] = 0;
        }

        return 0;
}

int
i915_gem_get_seqno(struct drm_device *dev, u32 *seqno)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        /* reserve 0 for non-seqno */
        if (dev_priv->next_seqno == 0) {
                int ret = i915_gem_handle_seqno_wrap(dev);
                if (ret)
                        return ret;

                dev_priv->next_seqno = 1;
        }

        *seqno = dev_priv->next_seqno++;
        return 0;
}

int
i915_add_request(struct intel_ring_buffer *ring,
                 struct drm_file *file,
                 u32 *out_seqno)
{
        drm_i915_private_t *dev_priv = ring->dev->dev_private;
        struct drm_i915_gem_request *request;
        u32 request_ring_position;
        int was_empty;
        int ret;

        /*
         * Emit any outstanding flushes - execbuf can fail to emit the flush
         * after having emitted the batchbuffer command. Hence we need to fix
         * things up similar to emitting the lazy request. The difference here
         * is that the flush _must_ happen before the next request, no matter
         * what.
         */
        if (ring->gpu_caches_dirty) {
                ret = i915_gem_flush_ring(ring, 0, I915_GEM_GPU_DOMAINS);
                if (ret)
                        return ret;

                ring->gpu_caches_dirty = false;
        }

        request = kmalloc(sizeof(*request), DRM_I915_GEM, M_WAITOK | M_ZERO);
        if (request == NULL)
                return -ENOMEM;

        /* Record the position of the start of the request so that
         * should we detect the updated seqno part-way through the
         * GPU processing the request, we never over-estimate the
         * position of the head.
         */
        request_ring_position = intel_ring_get_tail(ring);

        ret = ring->add_request(ring);
        if (ret) {
                kfree(request, DRM_I915_GEM);
                return ret;
        }

        request->seqno = intel_ring_get_seqno(ring);
        request->ring = ring;
        request->tail = request_ring_position;
        request->emitted_jiffies = jiffies;
        was_empty = list_empty(&ring->request_list);
        list_add_tail(&request->list, &ring->request_list);
        request->file_priv = NULL;

        if (file) {
                struct drm_i915_file_private *file_priv = file->driver_priv;

                spin_lock(&file_priv->mm.lock);
                request->file_priv = file_priv;
                list_add_tail(&request->client_list,
                              &file_priv->mm.request_list);
                spin_unlock(&file_priv->mm.lock);
        }

        ring->outstanding_lazy_request = 0;

        if (!dev_priv->mm.suspended) {
                if (i915_enable_hangcheck) {
                        mod_timer(&dev_priv->hangcheck_timer,
                                  round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES));
                }
                if (was_empty) {
                        queue_delayed_work(dev_priv->wq,
                                           &dev_priv->mm.retire_work,
                                           round_jiffies_up_relative(hz));
                        intel_mark_busy(dev_priv->dev);
                }
        }

        if (out_seqno)
                *out_seqno = request->seqno;
        return 0;
}

static inline void
i915_gem_request_remove_from_client(struct drm_i915_gem_request *request)
{
        struct drm_i915_file_private *file_priv = request->file_priv;

        if (!file_priv)
                return;

        DRM_LOCK_ASSERT(request->ring->dev);

        spin_lock(&file_priv->mm.lock);
        if (request->file_priv != NULL) {
                list_del(&request->client_list);
                request->file_priv = NULL;
        }
        spin_unlock(&file_priv->mm.lock);
}

static void
i915_gem_reset_ring_lists(struct drm_i915_private *dev_priv,
    struct intel_ring_buffer *ring)
{

        if (ring->dev != NULL)
                DRM_LOCK_ASSERT(ring->dev);

        while (!list_empty(&ring->request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&ring->request_list,
                    struct drm_i915_gem_request, list);

                list_del(&request->list);
                i915_gem_request_remove_from_client(request);
                drm_free(request, DRM_I915_GEM);
        }

        while (!list_empty(&ring->active_list)) {
                struct drm_i915_gem_object *obj;

                obj = list_first_entry(&ring->active_list,
                    struct drm_i915_gem_object, ring_list);

                list_del_init(&obj->gpu_write_list);
                i915_gem_object_move_to_inactive(obj);
        }
}

static void i915_gem_reset_fences(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int i;

        for (i = 0; i < dev_priv->num_fence_regs; i++) {
                struct drm_i915_fence_reg *reg = &dev_priv->fence_regs[i];

                i915_gem_write_fence(dev, i, NULL);

                if (reg->obj)
                        i915_gem_object_fence_lost(reg->obj);

                reg->pin_count = 0;
                reg->obj = NULL;
                INIT_LIST_HEAD(&reg->lru_list);
        }

        INIT_LIST_HEAD(&dev_priv->mm.fence_list);
}

void i915_gem_reset(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj;
        struct intel_ring_buffer *ring;
        int i;

        for_each_ring(ring, dev_priv, i)
                i915_gem_reset_ring_lists(dev_priv, ring);

        /* Move everything out of the GPU domains to ensure we do any
         * necessary invalidation upon reuse.
         */
        list_for_each_entry(obj,
                            &dev_priv->mm.inactive_list,
                            mm_list)
        {
                obj->base.read_domains &= ~I915_GEM_GPU_DOMAINS;
        }

        /* The fence registers are invalidated so clear them out */
        i915_gem_reset_fences(dev);
}

/**
 * This function clears the request list as sequence numbers are passed.
 */
void
i915_gem_retire_requests_ring(struct intel_ring_buffer *ring)
{
        uint32_t seqno;

        if (list_empty(&ring->request_list))
                return;

        WARN_ON(i915_verify_lists(ring->dev));

        seqno = ring->get_seqno(ring, true);

        while (!list_empty(&ring->request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&ring->request_list,
                                           struct drm_i915_gem_request,
                                           list);

                if (!i915_seqno_passed(seqno, request->seqno))
                        break;

                /* We know the GPU must have read the request to have
                 * sent us the seqno + interrupt, so use the position
                 * of tail of the request to update the last known position
                 * of the GPU head.
                 */
                ring->last_retired_head = request->tail;

                list_del(&request->list);
                i915_gem_request_remove_from_client(request);
                kfree(request, DRM_I915_GEM);
        }

        /* Move any buffers on the active list that are no longer referenced
         * by the ringbuffer to the flushing/inactive lists as appropriate.
         */
        while (!list_empty(&ring->active_list)) {
                struct drm_i915_gem_object *obj;

                obj = list_first_entry(&ring->active_list,
                                      struct drm_i915_gem_object,
                                      ring_list);

                if (!i915_seqno_passed(seqno, obj->last_read_seqno))
                        break;

                i915_gem_object_move_to_inactive(obj);
        }

        if (unlikely(ring->trace_irq_seqno &&
                     i915_seqno_passed(seqno, ring->trace_irq_seqno))) {
                ring->irq_put(ring);
                ring->trace_irq_seqno = 0;
        }

}

void
i915_gem_retire_requests(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct intel_ring_buffer *ring;
        int i;

        for_each_ring(ring, dev_priv, i)
                i915_gem_retire_requests_ring(ring);
}

static void
i915_gem_retire_work_handler(struct work_struct *work)
{
        drm_i915_private_t *dev_priv;
        struct drm_device *dev;
        struct intel_ring_buffer *ring;
        bool idle;
        int i;

        dev_priv = container_of(work, drm_i915_private_t,
                                mm.retire_work.work);
        dev = dev_priv->dev;

        /* Come back later if the device is busy... */
        if (lockmgr(&dev->dev_struct_lock, LK_EXCLUSIVE|LK_NOWAIT)) {
                queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work,
                                   round_jiffies_up_relative(hz));
                return;
        }

        i915_gem_retire_requests(dev);

        /* Send a periodic flush down the ring so we don't hold onto GEM
         * objects indefinitely.
         */
        idle = true;
        for_each_ring(ring, dev_priv, i) {
                if (ring->gpu_caches_dirty)
                        i915_add_request(ring, NULL, NULL);

                idle &= list_empty(&ring->request_list);
        }

        if (!dev_priv->mm.suspended && !idle)
                queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work,
                                   round_jiffies_up_relative(hz));
        if (idle)
                intel_mark_idle(dev);

        DRM_UNLOCK(dev);
}
/**
 * Ensures that an object will eventually get non-busy by flushing any required
 * write domains, emitting any outstanding lazy request and retiring and
 * completed requests.
 */
static int
i915_gem_object_flush_active(struct drm_i915_gem_object *obj)
{
        int ret;

        if (obj->active) {
                ret = i915_gem_object_flush_gpu_write_domain(obj);
                if (ret)
                        return ret;

                ret = i915_gem_check_olr(obj->ring, obj->last_read_seqno);
                if (ret)
                        return ret;

                i915_gem_retire_requests_ring(obj->ring);
        }

        return 0;
}

/**
 * i915_gem_wait_ioctl - implements DRM_IOCTL_I915_GEM_WAIT
 * @DRM_IOCTL_ARGS: standard ioctl arguments
 *
 * Returns 0 if successful, else an error is returned with the remaining time in
 * the timeout parameter.
 *  -ETIME: object is still busy after timeout
 *  -ERESTARTSYS: signal interrupted the wait
 *  -ENONENT: object doesn't exist
 * Also possible, but rare:
 *  -EAGAIN: GPU wedged
 *  -ENOMEM: damn
 *  -ENODEV: Internal IRQ fail
 *  -E?: The add request failed
 *
 * The wait ioctl with a timeout of 0 reimplements the busy ioctl. With any
 * non-zero timeout parameter the wait ioctl will wait for the given number of
 * nanoseconds on an object becoming unbusy. Since the wait itself does so
 * without holding struct_mutex the object may become re-busied before this
 * function completes. A similar but shorter * race condition exists in the busy
 * ioctl
 */
int
i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
{
        struct drm_i915_gem_wait *args = data;
        struct drm_i915_gem_object *obj;
        struct intel_ring_buffer *ring = NULL;
        struct timespec timeout_stack, *timeout = NULL;
        u32 seqno = 0;
        int ret = 0;

        if (args->timeout_ns >= 0) {
                timeout_stack = ns_to_timespec(args->timeout_ns);
                timeout = &timeout_stack;
        }

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->bo_handle));
        if (&obj->base == NULL) {
                DRM_UNLOCK(dev);
                return -ENOENT;
        }

        /* Need to make sure the object gets inactive eventually. */
        ret = i915_gem_object_flush_active(obj);
        if (ret)
                goto out;

        if (obj->active) {
                seqno = obj->last_read_seqno;
                ring = obj->ring;
        }

        if (seqno == 0)
                 goto out;

        /* Do this after OLR check to make sure we make forward progress polling
         * on this IOCTL with a 0 timeout (like busy ioctl)
         */
        if (!args->timeout_ns) {
                ret = -ETIMEDOUT;
                goto out;
        }

        drm_gem_object_unreference(&obj->base);
        DRM_UNLOCK(dev);

        ret = __wait_seqno(ring, seqno, true, timeout);
        if (timeout) {
                WARN_ON(!timespec_valid(timeout));
                args->timeout_ns = timespec_to_ns(timeout);
        }
        return ret;

out:
        drm_gem_object_unreference(&obj->base);
        DRM_UNLOCK(dev);
        return ret;
}

/**
 * i915_gem_object_sync - sync an object to a ring.
 *
 * @obj: object which may be in use on another ring.
 * @to: ring we wish to use the object on. May be NULL.
 *
 * This code is meant to abstract object synchronization with the GPU.
 * Calling with NULL implies synchronizing the object with the CPU
 * rather than a particular GPU ring.
 *
 * Returns 0 if successful, else propagates up the lower layer error.
 */
int
i915_gem_object_sync(struct drm_i915_gem_object *obj,
                     struct intel_ring_buffer *to)
{
        struct intel_ring_buffer *from = obj->ring;
        u32 seqno;
        int ret, idx;

        if (from == NULL || to == from)
                return 0;

        if (to == NULL || !i915_semaphore_is_enabled(obj->base.dev))
                return i915_gem_object_wait_rendering(obj, false);

        idx = intel_ring_sync_index(from, to);

        seqno = obj->last_read_seqno;
        if (seqno <= from->sync_seqno[idx])
                return 0;

        ret = i915_gem_check_olr(obj->ring, seqno);
        if (ret)
                return ret;

        ret = to->sync_to(to, from, seqno);
        if (!ret)
                from->sync_seqno[idx] = seqno;

        return ret;
}

static void i915_gem_object_finish_gtt(struct drm_i915_gem_object *obj)
{
        u32 old_write_domain, old_read_domains;

        /* Act a barrier for all accesses through the GTT */
        cpu_mfence();

        /* Force a pagefault for domain tracking on next user access */
        i915_gem_release_mmap(obj);

        if ((obj->base.read_domains & I915_GEM_DOMAIN_GTT) == 0)
                return;

        old_read_domains = obj->base.read_domains;
        old_write_domain = obj->base.write_domain;

        obj->base.read_domains &= ~I915_GEM_DOMAIN_GTT;
        obj->base.write_domain &= ~I915_GEM_DOMAIN_GTT;

}

/**
 * Unbinds an object from the GTT aperture.
 */
int
i915_gem_object_unbind(struct drm_i915_gem_object *obj)
{
        drm_i915_private_t *dev_priv = obj->base.dev->dev_private;
        int ret = 0;

        if (obj->gtt_space == NULL)
                return 0;

        if (obj->pin_count != 0) {
                DRM_ERROR("Attempting to unbind pinned buffer\n");
                return -EINVAL;
        }

        ret = i915_gem_object_finish_gpu(obj);
        if (ret)
                return ret;
        /* Continue on if we fail due to EIO, the GPU is hung so we
         * should be safe and we need to cleanup or else we might
         * cause memory corruption through use-after-free.
         */

        i915_gem_object_finish_gtt(obj);

        /* Move the object to the CPU domain to ensure that
         * any possible CPU writes while it's not in the GTT
         * are flushed when we go to remap it.
         */
        if (ret == 0)
                ret = i915_gem_object_set_to_cpu_domain(obj, 1);
        if (ret == -ERESTART || ret == -EINTR)
                return ret;
        if (ret) {
                /* In the event of a disaster, abandon all caches and
                 * hope for the best.
                 */
                i915_gem_clflush_object(obj);
                obj->base.read_domains = obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        /* release the fence reg _after_ flushing */
        ret = i915_gem_object_put_fence(obj);
        if (ret)
                return ret;

        if (obj->has_global_gtt_mapping)
                i915_gem_gtt_unbind_object(obj);
        if (obj->has_aliasing_ppgtt_mapping) {
                i915_ppgtt_unbind_object(dev_priv->mm.aliasing_ppgtt, obj);
                obj->has_aliasing_ppgtt_mapping = 0;
        }
        i915_gem_gtt_finish_object(obj);

        i915_gem_object_put_pages_gtt(obj);

        list_del_init(&obj->gtt_list);
        list_del_init(&obj->mm_list);
        /* Avoid an unnecessary call to unbind on rebind. */
        obj->map_and_fenceable = true;

        drm_mm_put_block(obj->gtt_space);
        obj->gtt_space = NULL;
        obj->gtt_offset = 0;

        if (i915_gem_object_is_purgeable(obj))
                i915_gem_object_truncate(obj);

        return ret;
}

int i915_gpu_idle(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct intel_ring_buffer *ring;
        int ret, i;

        /* Flush everything onto the inactive list. */
        for_each_ring(ring, dev_priv, i) {
                ret = intel_ring_idle(ring);
                if (ret)
                        return ret;
        }

        return 0;
}

static void sandybridge_write_fence_reg(struct drm_device *dev, int reg,
                                        struct drm_i915_gem_object *obj)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        uint64_t val;

        if (obj) {
                u32 size = obj->gtt_space->size;

                val = (uint64_t)((obj->gtt_offset + size - 4096) &
                                 0xfffff000) << 32;
                val |= obj->gtt_offset & 0xfffff000;
                val |= (uint64_t)((obj->stride / 128) - 1) <<
                        SANDYBRIDGE_FENCE_PITCH_SHIFT;

                if (obj->tiling_mode == I915_TILING_Y)
                        val |= 1 << I965_FENCE_TILING_Y_SHIFT;
                val |= I965_FENCE_REG_VALID;
        } else
                val = 0;

        I915_WRITE64(FENCE_REG_SANDYBRIDGE_0 + reg * 8, val);
        POSTING_READ(FENCE_REG_SANDYBRIDGE_0 + reg * 8);
}

static void i965_write_fence_reg(struct drm_device *dev, int reg,
                                 struct drm_i915_gem_object *obj)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        uint64_t val;

        if (obj) {
                u32 size = obj->gtt_space->size;

                val = (uint64_t)((obj->gtt_offset + size - 4096) &
                                 0xfffff000) << 32;
                val |= obj->gtt_offset & 0xfffff000;
                val |= ((obj->stride / 128) - 1) << I965_FENCE_PITCH_SHIFT;
                if (obj->tiling_mode == I915_TILING_Y)
                        val |= 1 << I965_FENCE_TILING_Y_SHIFT;
                val |= I965_FENCE_REG_VALID;
        } else
                val = 0;

        I915_WRITE64(FENCE_REG_965_0 + reg * 8, val);
        POSTING_READ(FENCE_REG_965_0 + reg * 8);
}

static void i915_write_fence_reg(struct drm_device *dev, int reg,
                                 struct drm_i915_gem_object *obj)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        u32 val;

        if (obj) {
                u32 size = obj->gtt_space->size;
                int pitch_val;
                int tile_width;

                WARN((obj->gtt_offset & ~I915_FENCE_START_MASK) ||
                     (size & -size) != size ||
                     (obj->gtt_offset & (size - 1)),
                     "object 0x%08x [fenceable? %d] not 1M or pot-size (0x%08x) aligned\n",
                     obj->gtt_offset, obj->map_and_fenceable, size);

                if (obj->tiling_mode == I915_TILING_Y && HAS_128_BYTE_Y_TILING(dev))
                        tile_width = 128;
                else
                        tile_width = 512;

                /* Note: pitch better be a power of two tile widths */
                pitch_val = obj->stride / tile_width;
                pitch_val = ffs(pitch_val) - 1;

                val = obj->gtt_offset;
                if (obj->tiling_mode == I915_TILING_Y)
                        val |= 1 << I830_FENCE_TILING_Y_SHIFT;
                val |= I915_FENCE_SIZE_BITS(size);
                val |= pitch_val << I830_FENCE_PITCH_SHIFT;
                val |= I830_FENCE_REG_VALID;
        } else
                val = 0;

        if (reg < 8)
                reg = FENCE_REG_830_0 + reg * 4;
        else
                reg = FENCE_REG_945_8 + (reg - 8) * 4;

        I915_WRITE(reg, val);
        POSTING_READ(reg);
}

static void i830_write_fence_reg(struct drm_device *dev, int reg,
                                struct drm_i915_gem_object *obj)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        uint32_t val;

        if (obj) {
                u32 size = obj->gtt_space->size;
                uint32_t pitch_val;

                WARN((obj->gtt_offset & ~I830_FENCE_START_MASK) ||
                     (size & -size) != size ||
                     (obj->gtt_offset & (size - 1)),
                     "object 0x%08x not 512K or pot-size 0x%08x aligned\n",
                     obj->gtt_offset, size);

                pitch_val = obj->stride / 128;
                pitch_val = ffs(pitch_val) - 1;

                val = obj->gtt_offset;
                if (obj->tiling_mode == I915_TILING_Y)
                        val |= 1 << I830_FENCE_TILING_Y_SHIFT;
                val |= I830_FENCE_SIZE_BITS(size);
                val |= pitch_val << I830_FENCE_PITCH_SHIFT;
                val |= I830_FENCE_REG_VALID;
        } else
                val = 0;

        I915_WRITE(FENCE_REG_830_0 + reg * 4, val);
        POSTING_READ(FENCE_REG_830_0 + reg * 4);
}

static void i915_gem_write_fence(struct drm_device *dev, int reg,
                                 struct drm_i915_gem_object *obj)
{
        switch (INTEL_INFO(dev)->gen) {
        case 7:
        case 6: sandybridge_write_fence_reg(dev, reg, obj); break;
        case 5:
        case 4: i965_write_fence_reg(dev, reg, obj); break;
        case 3: i915_write_fence_reg(dev, reg, obj); break;
        case 2: i830_write_fence_reg(dev, reg, obj); break;
        default: break;
        }
}

static inline int fence_number(struct drm_i915_private *dev_priv,
                               struct drm_i915_fence_reg *fence)
{
        return fence - dev_priv->fence_regs;
}

static void i915_gem_object_update_fence(struct drm_i915_gem_object *obj,
                                         struct drm_i915_fence_reg *fence,
                                         bool enable)
{
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        int reg = fence_number(dev_priv, fence);

        i915_gem_write_fence(obj->base.dev, reg, enable ? obj : NULL);

        if (enable) {
                obj->fence_reg = reg;
                fence->obj = obj;
                list_move_tail(&fence->lru_list, &dev_priv->mm.fence_list);
        } else {
                obj->fence_reg = I915_FENCE_REG_NONE;
                fence->obj = NULL;
                list_del_init(&fence->lru_list);
        }
}

static int
i915_gem_object_flush_fence(struct drm_i915_gem_object *obj)
{
        int ret;

        if (obj->fenced_gpu_access) {
                if (obj->base.write_domain & I915_GEM_GPU_DOMAINS) {
                        ret = i915_gem_flush_ring(obj->ring,
                                                  0, obj->base.write_domain);
                        if (ret)
                                return ret;
                }

                obj->fenced_gpu_access = false;
        }

        if (obj->last_fenced_seqno) {
                ret = i915_wait_seqno(obj->ring,
                                        obj->last_fenced_seqno);
                if (ret)
                        return ret;

                obj->last_fenced_seqno = 0;
        }

        /* Ensure that all CPU reads are completed before installing a fence
         * and all writes before removing the fence.
         */
        if (obj->base.read_domains & I915_GEM_DOMAIN_GTT)
                cpu_mfence();

        return 0;
}

int
i915_gem_object_put_fence(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        int ret;

        ret = i915_gem_object_flush_fence(obj);
        if (ret)
                return ret;

        if (obj->fence_reg == I915_FENCE_REG_NONE)
                return 0;

        i915_gem_object_update_fence(obj,
                                     &dev_priv->fence_regs[obj->fence_reg],
                                     false);
        i915_gem_object_fence_lost(obj);

        return 0;
}

static struct drm_i915_fence_reg *
i915_find_fence_reg(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_fence_reg *reg, *avail;
        int i;

        /* First try to find a free reg */
        avail = NULL;
        for (i = dev_priv->fence_reg_start; i < dev_priv->num_fence_regs; i++) {
                reg = &dev_priv->fence_regs[i];
                if (!reg->obj)
                        return reg;

                if (!reg->pin_count)
                        avail = reg;
        }

        if (avail == NULL)
                return NULL;

        /* None available, try to steal one or wait for a user to finish */
        list_for_each_entry(reg, &dev_priv->mm.fence_list, lru_list) {
                if (reg->pin_count)
                        continue;

                return reg;
        }

        return NULL;
}

/**
 * i915_gem_object_get_fence - set up fencing for an object
 * @obj: object to map through a fence reg
 *
 * When mapping objects through the GTT, userspace wants to be able to write
 * to them without having to worry about swizzling if the object is tiled.
 * This function walks the fence regs looking for a free one for @obj,
 * stealing one if it can't find any.
 *
 * It then sets up the reg based on the object's properties: address, pitch
 * and tiling format.
 *
 * For an untiled surface, this removes any existing fence.
 */
int
i915_gem_object_get_fence(struct drm_i915_gem_object *obj)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        bool enable = obj->tiling_mode != I915_TILING_NONE;
        struct drm_i915_fence_reg *reg;
        int ret;

        /* Have we updated the tiling parameters upon the object and so
         * will need to serialise the write to the associated fence register?
         */
        if (obj->fence_dirty) {
                ret = i915_gem_object_flush_fence(obj);
                if (ret)
                        return ret;
        }

        /* Just update our place in the LRU if our fence is getting reused. */
        if (obj->fence_reg != I915_FENCE_REG_NONE) {
                reg = &dev_priv->fence_regs[obj->fence_reg];
                if (!obj->fence_dirty) {
                        list_move_tail(&reg->lru_list,
                                       &dev_priv->mm.fence_list);
                        return 0;
                }
        } else if (enable) {
                reg = i915_find_fence_reg(dev);
                if (reg == NULL)
                        return -EDEADLK;

                if (reg->obj) {
                        struct drm_i915_gem_object *old = reg->obj;

                        ret = i915_gem_object_flush_fence(old);
                        if (ret)
                                return ret;

                        i915_gem_object_fence_lost(old);
                }
        } else
                return 0;

        i915_gem_object_update_fence(obj, reg, enable);
        obj->fence_dirty = false;

        return 0;
}

static int
i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
    unsigned alignment, bool map_and_fenceable)
{
        struct drm_device *dev;
        struct drm_i915_private *dev_priv;
        struct drm_mm_node *free_space;
        uint32_t size, fence_size, fence_alignment, unfenced_alignment;
        bool mappable, fenceable;
        int ret;
        bool nonblocking = false;

        dev = obj->base.dev;
        dev_priv = dev->dev_private;

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_ERROR("Attempting to bind a purgeable object\n");
                return (-EINVAL);
        }

        fence_size = i915_gem_get_gtt_size(dev, obj->base.size,
            obj->tiling_mode);
        fence_alignment = i915_gem_get_gtt_alignment(dev, obj->base.size,
            obj->tiling_mode);
        unfenced_alignment = i915_gem_get_unfenced_gtt_alignment(dev,
            obj->base.size, obj->tiling_mode);
        if (alignment == 0)
                alignment = map_and_fenceable ? fence_alignment :
                    unfenced_alignment;
        if (map_and_fenceable && (alignment & (fence_alignment - 1)) != 0) {
                DRM_ERROR("Invalid object alignment requested %u\n", alignment);
                return (-EINVAL);
        }

        size = map_and_fenceable ? fence_size : obj->base.size;

        /* If the object is bigger than the entire aperture, reject it early
         * before evicting everything in a vain attempt to find space.
         */
        if (obj->base.size > (map_and_fenceable ?
            dev_priv->mm.gtt_mappable_end : dev_priv->mm.gtt_total)) {
                DRM_ERROR(
"Attempting to bind an object larger than the aperture\n");
                return (-E2BIG);
        }

 search_free:
        if (map_and_fenceable)
                free_space = drm_mm_search_free_in_range(
                    &dev_priv->mm.gtt_space, size, alignment, 0,
                    dev_priv->mm.gtt_mappable_end, 0);
        else
                free_space = drm_mm_search_free(&dev_priv->mm.gtt_space,
                    size, alignment, 0);
        if (free_space != NULL) {
                int color = 0;
                if (map_and_fenceable)
                        obj->gtt_space = drm_mm_get_block_range_generic(
                            free_space, size, alignment, color, 0,
                            dev_priv->mm.gtt_mappable_end, 1);
                else
                        obj->gtt_space = drm_mm_get_block_generic(free_space,
                            size, alignment, color, 1);
        }
        if (obj->gtt_space == NULL) {
                ret = i915_gem_evict_something(dev, size, alignment,
                                               obj->cache_level,
                                               map_and_fenceable,
                                               nonblocking);
                if (ret != 0)
                        return (ret);
                goto search_free;
        }

        /*
         * NOTE: i915_gem_object_get_pages_gtt() cannot
         *       return ENOMEM, since we used VM_ALLOC_RETRY.
         */
        ret = i915_gem_object_get_pages_gtt(obj, 0);
        if (ret != 0) {
                drm_mm_put_block(obj->gtt_space);
                obj->gtt_space = NULL;
                return (ret);
        }

        i915_gem_gtt_bind_object(obj, obj->cache_level);
        if (ret != 0) {
                i915_gem_object_put_pages_gtt(obj);
                drm_mm_put_block(obj->gtt_space);
                obj->gtt_space = NULL;
                if (i915_gem_evict_everything(dev))
                        return (ret);
                goto search_free;
        }

        list_add_tail(&obj->gtt_list, &dev_priv->mm.gtt_list);
        list_add_tail(&obj->mm_list, &dev_priv->mm.inactive_list);

        obj->gtt_offset = obj->gtt_space->start;

        fenceable =
                obj->gtt_space->size == fence_size &&
                (obj->gtt_space->start & (fence_alignment - 1)) == 0;

        mappable =
                obj->gtt_offset + obj->base.size <= dev_priv->mm.gtt_mappable_end;
        obj->map_and_fenceable = mappable && fenceable;

        return (0);
}

void
i915_gem_clflush_object(struct drm_i915_gem_object *obj)
{

        /* If we don't have a page list set up, then we're not pinned
         * to GPU, and we can ignore the cache flush because it'll happen
         * again at bind time.
         */
        if (obj->pages == NULL)
                return;

        /* If the GPU is snooping the contents of the CPU cache,
         * we do not need to manually clear the CPU cache lines.  However,
         * the caches are only snooped when the render cache is
         * flushed/invalidated.  As we always have to emit invalidations
         * and flushes when moving into and out of the RENDER domain, correct
         * snooping behaviour occurs naturally as the result of our domain
         * tracking.
         */
        if (obj->cache_level != I915_CACHE_NONE)
                return;

        drm_clflush_pages(obj->pages, obj->base.size / PAGE_SIZE);
}

/** Flushes the GTT write domain for the object if it's dirty. */
static void
i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj)
{
        uint32_t old_write_domain;

        if (obj->base.write_domain != I915_GEM_DOMAIN_GTT)
                return;

        /* No actual flushing is required for the GTT write domain.  Writes
         * to it immediately go to main memory as far as we know, so there's
         * no chipset flush.  It also doesn't land in render cache.
         *
         * However, we do have to enforce the order so that all writes through
         * the GTT land before any writes to the device, such as updates to
         * the GATT itself.
         */
        cpu_sfence();

        old_write_domain = obj->base.write_domain;
        obj->base.write_domain = 0;
}

/** Flushes the CPU write domain for the object if it's dirty. */
static void
i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj)
{
        uint32_t old_write_domain;

        if (obj->base.write_domain != I915_GEM_DOMAIN_CPU)
                return;

        i915_gem_clflush_object(obj);
        intel_gtt_chipset_flush();
        old_write_domain = obj->base.write_domain;
        obj->base.write_domain = 0;
}

static int
i915_gem_object_flush_gpu_write_domain(struct drm_i915_gem_object *obj)
{

        if ((obj->base.write_domain & I915_GEM_GPU_DOMAINS) == 0)
                return (0);
        return (i915_gem_flush_ring(obj->ring, 0, obj->base.write_domain));
}

/**
 * Moves a single object to the GTT read, and possibly write domain.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
int
i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
{
        drm_i915_private_t *dev_priv = obj->base.dev->dev_private;
        uint32_t old_write_domain, old_read_domains;
        int ret;

        /* Not valid to be called on unbound objects. */
        if (obj->gtt_space == NULL)
                return -EINVAL;

        if (obj->base.write_domain == I915_GEM_DOMAIN_GTT)
                return 0;

        ret = i915_gem_object_flush_gpu_write_domain(obj);
        if (ret)
                return ret;

        ret = i915_gem_object_wait_rendering(obj, !write);
        if (ret)
                return ret;

        i915_gem_object_flush_cpu_write_domain(obj);

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_GTT) != 0);
        obj->base.read_domains |= I915_GEM_DOMAIN_GTT;
        if (write) {
                obj->base.read_domains = I915_GEM_DOMAIN_GTT;
                obj->base.write_domain = I915_GEM_DOMAIN_GTT;
                obj->dirty = 1;
        }

        /* And bump the LRU for this access */
        if (i915_gem_object_is_inactive(obj))
                list_move_tail(&obj->mm_list, &dev_priv->mm.inactive_list);

        return 0;
}

int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
                                    enum i915_cache_level cache_level)
{
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret;

        if (obj->cache_level == cache_level)
                return 0;

        if (obj->pin_count) {
                DRM_DEBUG("can not change the cache level of pinned objects\n");
                return -EBUSY;
        }

        if (obj->gtt_space) {
                ret = i915_gem_object_finish_gpu(obj);
                if (ret != 0)
                        return (ret);

                i915_gem_object_finish_gtt(obj);

                /* Before SandyBridge, you could not use tiling or fence
                 * registers with snooped memory, so relinquish any fences
                 * currently pointing to our region in the aperture.
                 */
                if (INTEL_INFO(obj->base.dev)->gen < 6) {
                        ret = i915_gem_object_put_fence(obj);
                        if (ret)
                                return ret;
                }

                if (obj->has_global_gtt_mapping)
                        i915_gem_gtt_bind_object(obj, cache_level);
                if (obj->has_aliasing_ppgtt_mapping)
                        i915_ppgtt_bind_object(dev_priv->mm.aliasing_ppgtt,
                                               obj, cache_level);
        }

        if (cache_level == I915_CACHE_NONE) {
                u32 old_read_domains, old_write_domain;

                /* If we're coming from LLC cached, then we haven't
                 * actually been tracking whether the data is in the
                 * CPU cache or not, since we only allow one bit set
                 * in obj->write_domain and have been skipping the clflushes.
                 * Just set it to the CPU cache for now.
                 */
                KASSERT((obj->base.write_domain & ~I915_GEM_DOMAIN_CPU) == 0,
                    ("obj %p in CPU write domain", obj));
                KASSERT((obj->base.read_domains & ~I915_GEM_DOMAIN_CPU) == 0,
                    ("obj %p in CPU read domain", obj));

                old_read_domains = obj->base.read_domains;
                old_write_domain = obj->base.write_domain;

                obj->base.read_domains = I915_GEM_DOMAIN_CPU;
                obj->base.write_domain = I915_GEM_DOMAIN_CPU;

        }

        obj->cache_level = cache_level;
        return 0;
}

int i915_gem_get_caching_ioctl(struct drm_device *dev, void *data,
                               struct drm_file *file)
{
        struct drm_i915_gem_caching *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        args->caching = obj->cache_level != I915_CACHE_NONE;

        drm_gem_object_unreference(&obj->base);
unlock:
        DRM_UNLOCK(dev);
        return ret;
}

int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data,
                               struct drm_file *file)
{
        struct drm_i915_gem_caching *args = data;
        struct drm_i915_gem_object *obj;
        enum i915_cache_level level;
        int ret;

        switch (args->caching) {
        case I915_CACHING_NONE:
                level = I915_CACHE_NONE;
                break;
        case I915_CACHING_CACHED:
                level = I915_CACHE_LLC;
                break;
        default:
                return -EINVAL;
        }

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        ret = i915_gem_object_set_cache_level(obj, level);

        drm_gem_object_unreference(&obj->base);
unlock:
        DRM_UNLOCK(dev);
        return ret;
}

/*
 * Prepare buffer for display plane (scanout, cursors, etc).
 * Can be called from an uninterruptible phase (modesetting) and allows
 * any flushes to be pipelined (for pageflips).
 */
int
i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
                                     u32 alignment,
                                     struct intel_ring_buffer *pipelined)
{
        u32 old_read_domains, old_write_domain;
        int ret;

        ret = i915_gem_object_flush_gpu_write_domain(obj);
        if (ret)
                return ret;

        if (pipelined != obj->ring) {
                ret = i915_gem_object_sync(obj, pipelined);
                if (ret)
                        return ret;
        }

        /* The display engine is not coherent with the LLC cache on gen6.  As
         * a result, we make sure that the pinning that is about to occur is
         * done with uncached PTEs. This is lowest common denominator for all
         * chipsets.
         *
         * However for gen6+, we could do better by using the GFDT bit instead
         * of uncaching, which would allow us to flush all the LLC-cached data
         * with that bit in the PTE to main memory with just one PIPE_CONTROL.
         */
        ret = i915_gem_object_set_cache_level(obj, I915_CACHE_NONE);
        if (ret)
                return ret;

        /* As the user may map the buffer once pinned in the display plane
         * (e.g. libkms for the bootup splash), we have to ensure that we
         * always use map_and_fenceable for all scanout buffers.
         */
        ret = i915_gem_object_pin(obj, alignment, true);
        if (ret)
                return ret;

        i915_gem_object_flush_cpu_write_domain(obj);

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        obj->base.write_domain = 0;
        obj->base.read_domains |= I915_GEM_DOMAIN_GTT;

        return 0;
}

int
i915_gem_object_finish_gpu(struct drm_i915_gem_object *obj)
{
        int ret;

        if ((obj->base.read_domains & I915_GEM_GPU_DOMAINS) == 0)
                return 0;

        if (obj->base.write_domain & I915_GEM_GPU_DOMAINS) {
                ret = i915_gem_flush_ring(obj->ring, 0, obj->base.write_domain);
                if (ret)
                        return ret;
        }

        ret = i915_gem_object_wait_rendering(obj, false);
        if (ret)
                return ret;

        /* Ensure that we invalidate the GPU's caches and TLBs. */
        obj->base.read_domains &= ~I915_GEM_GPU_DOMAINS;
        return 0;
}

/**
 * Moves a single object to the CPU read, and possibly write domain.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
int
i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj, bool write)
{
        uint32_t old_write_domain, old_read_domains;
        int ret;

        if (obj->base.write_domain == I915_GEM_DOMAIN_CPU)
                return 0;

        ret = i915_gem_object_flush_gpu_write_domain(obj);
        if (ret)
                return ret;

        ret = i915_gem_object_wait_rendering(obj, !write);
        if (ret)
                return ret;

        i915_gem_object_flush_gtt_write_domain(obj);

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* Flush the CPU cache if it's still invalid. */
        if ((obj->base.read_domains & I915_GEM_DOMAIN_CPU) == 0) {
                i915_gem_clflush_object(obj);

                obj->base.read_domains |= I915_GEM_DOMAIN_CPU;
        }

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_CPU) != 0);

        /* If we're writing through the CPU, then the GPU read domains will
         * need to be invalidated at next use.
         */
        if (write) {
                obj->base.read_domains = I915_GEM_DOMAIN_CPU;
                obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        return 0;
}

/* Throttle our rendering by waiting until the ring has completed our requests
 * emitted over 20 msec ago.
 *
 * Note that if we were to use the current jiffies each time around the loop,
 * we wouldn't escape the function with any frames outstanding if the time to
 * render a frame was over 20ms.
 *
 * This should get us reasonable parallelism between CPU and GPU but also
 * relatively low latency when blocking on a particular request to finish.
 */
static int
i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_file_private *file_priv = file->driver_priv;
        unsigned long recent_enough = ticks - (20 * hz / 1000);
        struct drm_i915_gem_request *request;
        struct intel_ring_buffer *ring = NULL;
        u32 seqno = 0;
        int ret;

        if (atomic_read(&dev_priv->mm.wedged))
                return -EIO;

        spin_lock(&file_priv->mm.lock);
        list_for_each_entry(request, &file_priv->mm.request_list, client_list) {
                if (time_after_eq(request->emitted_jiffies, recent_enough))
                        break;

                ring = request->ring;
                seqno = request->seqno;
        }
        spin_unlock(&file_priv->mm.lock);

        if (seqno == 0)
                return 0;

        ret = __wait_seqno(ring, seqno, true, NULL);

        if (ret == 0)
                queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, 0);

        return ret;
}

int
i915_gem_object_pin(struct drm_i915_gem_object *obj,
                    uint32_t alignment,
                    bool map_and_fenceable)
{
        int ret;

        if (WARN_ON(obj->pin_count == DRM_I915_GEM_OBJECT_MAX_PIN_COUNT))
                return -EBUSY;

        if (obj->gtt_space != NULL) {
                if ((alignment && obj->gtt_offset & (alignment - 1)) ||
                    (map_and_fenceable && !obj->map_and_fenceable)) {
                        WARN(obj->pin_count,
                             "bo is already pinned with incorrect alignment:"
                             " offset=%x, req.alignment=%x, req.map_and_fenceable=%d,"
                             " obj->map_and_fenceable=%d\n",
                             obj->gtt_offset, alignment,
                             map_and_fenceable,
                             obj->map_and_fenceable);
                        ret = i915_gem_object_unbind(obj);
                        if (ret)
                                return ret;
                }
        }

        if (obj->gtt_space == NULL) {
                ret = i915_gem_object_bind_to_gtt(obj, alignment,
                                                  map_and_fenceable);
                if (ret)
                        return ret;
        }

        if (!obj->has_global_gtt_mapping && map_and_fenceable)
                i915_gem_gtt_bind_object(obj, obj->cache_level);

        obj->pin_count++;
        obj->pin_mappable |= map_and_fenceable;

        return 0;
}

void
i915_gem_object_unpin(struct drm_i915_gem_object *obj)
{
        BUG_ON(obj->pin_count == 0);
        BUG_ON(obj->gtt_space == NULL);

        if (--obj->pin_count == 0)
                obj->pin_mappable = false;
}

int
i915_gem_pin_ioctl(struct drm_device *dev, void *data,
    struct drm_file *file)
{
        struct drm_i915_gem_pin *args;
        struct drm_i915_gem_object *obj;
        struct drm_gem_object *gobj;
        int ret;

        args = data;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret != 0)
                return ret;

        gobj = drm_gem_object_lookup(dev, file, args->handle);
        if (gobj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }
        obj = to_intel_bo(gobj);

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_ERROR("Attempting to pin a purgeable buffer\n");
                ret = -EINVAL;
                goto out;
        }

        if (obj->pin_filp != NULL && obj->pin_filp != file) {
                DRM_ERROR("Already pinned in i915_gem_pin_ioctl(): %d\n",
                    args->handle);
                ret = -EINVAL;
                goto out;
        }

        obj->user_pin_count++;
        obj->pin_filp = file;
        if (obj->user_pin_count == 1) {
                ret = i915_gem_object_pin(obj, args->alignment, true);
                if (ret != 0)
                        goto out;
        }

        /* XXX - flush the CPU caches for pinned objects
         * as the X server doesn't manage domains yet
         */
        i915_gem_object_flush_cpu_write_domain(obj);
        args->offset = obj->gtt_offset;
out:
        drm_gem_object_unreference(&obj->base);
unlock:
        DRM_UNLOCK(dev);
        return (ret);
}

int
i915_gem_unpin_ioctl(struct drm_device *dev, void *data,
    struct drm_file *file)
{
        struct drm_i915_gem_pin *args;
        struct drm_i915_gem_object *obj;
        int ret;

        args = data;
        ret = i915_mutex_lock_interruptible(dev);
        if (ret != 0)
                return (ret);

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (obj->pin_filp != file) {
                DRM_ERROR("Not pinned by caller in i915_gem_pin_ioctl(): %d\n",
                    args->handle);
                ret = -EINVAL;
                goto out;
        }
        obj->user_pin_count--;
        if (obj->user_pin_count == 0) {
                obj->pin_filp = NULL;
                i915_gem_object_unpin(obj);
        }

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        DRM_UNLOCK(dev);
        return (ret);
}

int
i915_gem_busy_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_busy *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Count all active objects as busy, even if they are currently not used
         * by the gpu. Users of this interface expect objects to eventually
         * become non-busy without any further actions, therefore emit any
         * necessary flushes here.
         */
        ret = i915_gem_object_flush_active(obj);

        args->busy = obj->active;
        if (obj->ring) {
                args->busy |= intel_ring_flag(obj->ring) << 17;
        }

        drm_gem_object_unreference(&obj->base);
unlock:
        DRM_UNLOCK(dev);
        return ret;
}

int
i915_gem_throttle_ioctl(struct drm_device *dev, void *data,
    struct drm_file *file_priv)
{

        return (i915_gem_ring_throttle(dev, file_priv));
}

int
i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        struct drm_i915_gem_madvise *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        switch (args->madv) {
        case I915_MADV_DONTNEED:
        case I915_MADV_WILLNEED:
            break;
        default:
            return -EINVAL;
        }

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file_priv, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (obj->pin_count) {
                ret = -EINVAL;
                goto out;
        }

        if (obj->madv != __I915_MADV_PURGED)
                obj->madv = args->madv;

        /* if the object is no longer attached, discard its backing storage */
        if (i915_gem_object_is_purgeable(obj) && obj->pages == NULL)
                i915_gem_object_truncate(obj);

        args->retained = obj->madv != __I915_MADV_PURGED;

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        DRM_UNLOCK(dev);
        return ret;
}

struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev,
                                                  size_t size)
{
        struct drm_i915_private *dev_priv;
        struct drm_i915_gem_object *obj;

        dev_priv = dev->dev_private;

        obj = kmalloc(sizeof(*obj), DRM_I915_GEM, M_WAITOK | M_ZERO);

        if (drm_gem_object_init(dev, &obj->base, size) != 0) {
                drm_free(obj, DRM_I915_GEM);
                return (NULL);
        }

        obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        obj->base.read_domains = I915_GEM_DOMAIN_CPU;

        if (HAS_LLC(dev))
                obj->cache_level = I915_CACHE_LLC;
        else
                obj->cache_level = I915_CACHE_NONE;
        obj->base.driver_private = NULL;
        obj->fence_reg = I915_FENCE_REG_NONE;
        INIT_LIST_HEAD(&obj->mm_list);
        INIT_LIST_HEAD(&obj->gtt_list);
        INIT_LIST_HEAD(&obj->ring_list);
        INIT_LIST_HEAD(&obj->exec_list);
        INIT_LIST_HEAD(&obj->gpu_write_list);
        obj->madv = I915_MADV_WILLNEED;
        /* Avoid an unnecessary call to unbind on the first bind. */
        obj->map_and_fenceable = true;

        i915_gem_info_add_obj(dev_priv, size);

        return (obj);
}

int i915_gem_init_object(struct drm_gem_object *obj)
{
        BUG();

        return 0;
}

void i915_gem_free_object(struct drm_gem_object *gem_obj)
{
        struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
        struct drm_device *dev = obj->base.dev;
        drm_i915_private_t *dev_priv = dev->dev_private;

        if (obj->phys_obj)
                i915_gem_detach_phys_object(dev, obj);

        obj->pin_count = 0;
        if (WARN_ON(i915_gem_object_unbind(obj) == -ERESTARTSYS)) {
                bool was_interruptible;

                was_interruptible = dev_priv->mm.interruptible;
                dev_priv->mm.interruptible = false;

                WARN_ON(i915_gem_object_unbind(obj));

                dev_priv->mm.interruptible = was_interruptible;
        }

        drm_gem_free_mmap_offset(&obj->base);

        drm_gem_object_release(&obj->base);
        i915_gem_info_remove_obj(dev_priv, obj->base.size);

        drm_free(obj->bit_17, DRM_I915_GEM);
        drm_free(obj, DRM_I915_GEM);
}

int
i915_gem_do_init(struct drm_device *dev, unsigned long start,
    unsigned long mappable_end, unsigned long end)
{
        drm_i915_private_t *dev_priv;
        unsigned long mappable;
        int error;

        dev_priv = dev->dev_private;
        mappable = min(end, mappable_end) - start;

        drm_mm_init(&dev_priv->mm.gtt_space, start, end - start);

        dev_priv->mm.gtt_start = start;
        dev_priv->mm.gtt_mappable_end = mappable_end;
        dev_priv->mm.gtt_end = end;
        dev_priv->mm.gtt_total = end - start;
        dev_priv->mm.mappable_gtt_total = mappable;

        /* Take over this portion of the GTT */
        intel_gtt_clear_range(start / PAGE_SIZE, (end-start) / PAGE_SIZE);
        device_printf(dev->dev,
            "taking over the fictitious range 0x%lx-0x%lx\n",
            dev->agp->base + start, dev->agp->base + start + mappable);
        error = -vm_phys_fictitious_reg_range(dev->agp->base + start,
            dev->agp->base + start + mappable, VM_MEMATTR_WRITE_COMBINING);
        return (error);
}

int
i915_gem_idle(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret;

        DRM_LOCK(dev);

        if (dev_priv->mm.suspended) {
                DRM_UNLOCK(dev);
                return 0;
        }

        ret = i915_gpu_idle(dev);
        if (ret) {
                DRM_UNLOCK(dev);
                return ret;
        }
        i915_gem_retire_requests(dev);

        /* Under UMS, be paranoid and evict. */
        if (!drm_core_check_feature(dev, DRIVER_MODESET))
                i915_gem_evict_everything(dev);

        i915_gem_reset_fences(dev);

        /* Hack!  Don't let anybody do execbuf while we don't control the chip.
         * We need to replace this with a semaphore, or something.
         * And not confound mm.suspended!
         */
        dev_priv->mm.suspended = 1;
        del_timer_sync(&dev_priv->hangcheck_timer);

        i915_kernel_lost_context(dev);
        i915_gem_cleanup_ringbuffer(dev);

        DRM_UNLOCK(dev);

        /* Cancel the retire work handler, which should be idle now. */
        cancel_delayed_work_sync(&dev_priv->mm.retire_work);

        return 0;
}

void i915_gem_l3_remap(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        u32 misccpctl;
        int i;

        if (!HAS_L3_GPU_CACHE(dev))
                return;

        if (!dev_priv->l3_parity.remap_info)
                return;

        misccpctl = I915_READ(GEN7_MISCCPCTL);
        I915_WRITE(GEN7_MISCCPCTL, misccpctl & ~GEN7_DOP_CLOCK_GATE_ENABLE);
        POSTING_READ(GEN7_MISCCPCTL);

        for (i = 0; i < GEN7_L3LOG_SIZE; i += 4) {
                u32 remap = I915_READ(GEN7_L3LOG_BASE + i);
                if (remap && remap != dev_priv->l3_parity.remap_info[i/4])
                        DRM_DEBUG("0x%x was already programmed to %x\n",
                                  GEN7_L3LOG_BASE + i, remap);
                if (remap && !dev_priv->l3_parity.remap_info[i/4])
                        DRM_DEBUG_DRIVER("Clearing remapped register\n");
                I915_WRITE(GEN7_L3LOG_BASE + i, dev_priv->l3_parity.remap_info[i/4]);
        }

        /* Make sure all the writes land before disabling dop clock gating */
        POSTING_READ(GEN7_L3LOG_BASE);

        I915_WRITE(GEN7_MISCCPCTL, misccpctl);
}

void
i915_gem_init_swizzling(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv;

        dev_priv = dev->dev_private;

        if (INTEL_INFO(dev)->gen < 5 ||
            dev_priv->mm.bit_6_swizzle_x == I915_BIT_6_SWIZZLE_NONE)
                return;

        I915_WRITE(DISP_ARB_CTL, I915_READ(DISP_ARB_CTL) |
                                 DISP_TILE_SURFACE_SWIZZLING);

        if (IS_GEN5(dev))
                return;

        I915_WRITE(TILECTL, I915_READ(TILECTL) | TILECTL_SWZCTL);
        if (IS_GEN6(dev))
                I915_WRITE(ARB_MODE, _MASKED_BIT_ENABLE(ARB_MODE_SWIZZLE_SNB));
        else
                I915_WRITE(ARB_MODE, _MASKED_BIT_ENABLE(ARB_MODE_SWIZZLE_IVB));
}

static bool
intel_enable_blt(struct drm_device *dev)
{
        int revision;

        if (!HAS_BLT(dev))
                return false;

        /* The blitter was dysfunctional on early prototypes */
        revision = pci_read_config(dev->dev, PCIR_REVID, 1);
        if (IS_GEN6(dev) && revision < 8) {
                DRM_INFO("BLT not supported on this pre-production hardware;"
                         " graphics performance will be degraded.\n");
                return false;
        }

        return true;
}

int
i915_gem_init_hw(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret;

        if (IS_HASWELL(dev) && (I915_READ(0x120010) == 1))
                I915_WRITE(0x9008, I915_READ(0x9008) | 0xf0000);

        i915_gem_l3_remap(dev);

        i915_gem_init_swizzling(dev);

        ret = intel_init_render_ring_buffer(dev);
        if (ret)
                return ret;

        if (HAS_BSD(dev)) {
                ret = intel_init_bsd_ring_buffer(dev);
                if (ret)
                        goto cleanup_render_ring;
        }

        if (intel_enable_blt(dev)) {
                ret = intel_init_blt_ring_buffer(dev);
                if (ret)
                        goto cleanup_bsd_ring;
        }

        dev_priv->next_seqno = 1;

        /*
         * XXX: There was some w/a described somewhere suggesting loading
         * contexts before PPGTT.
         */
#if 0   /* XXX: HW context support */
        i915_gem_context_init(dev);
#endif
        i915_gem_init_ppgtt(dev);

        return 0;

cleanup_bsd_ring:
        intel_cleanup_ring_buffer(&dev_priv->ring[VCS]);
cleanup_render_ring:
        intel_cleanup_ring_buffer(&dev_priv->ring[RCS]);
        return ret;
}

static bool
intel_enable_ppgtt(struct drm_device *dev)
{
        if (i915_enable_ppgtt >= 0)
                return i915_enable_ppgtt;

        /* Disable ppgtt on SNB if VT-d is on. */
        if (INTEL_INFO(dev)->gen == 6 && intel_iommu_enabled)
                return false;

        return true;
}

int i915_gem_init(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        unsigned long prealloc_size, gtt_size, mappable_size;
        int ret;

        prealloc_size = dev_priv->mm.gtt->stolen_size;
        gtt_size = dev_priv->mm.gtt->gtt_total_entries << PAGE_SHIFT;
        mappable_size = dev_priv->mm.gtt->gtt_mappable_entries << PAGE_SHIFT;

        /* Basic memrange allocator for stolen space */
        drm_mm_init(&dev_priv->mm.stolen, 0, prealloc_size);

        DRM_LOCK(dev);
        if (intel_enable_ppgtt(dev) && HAS_ALIASING_PPGTT(dev)) {
                /* PPGTT pdes are stolen from global gtt ptes, so shrink the
                 * aperture accordingly when using aliasing ppgtt. */
                gtt_size -= I915_PPGTT_PD_ENTRIES*PAGE_SIZE;
                /* For paranoia keep the guard page in between. */
                gtt_size -= PAGE_SIZE;

                i915_gem_do_init(dev, 0, mappable_size, gtt_size);

                ret = i915_gem_init_aliasing_ppgtt(dev);
                if (ret) {
                        DRM_UNLOCK(dev);
                        return ret;
                }
        } else {
                /* Let GEM Manage all of the aperture.
                 *
                 * However, leave one page at the end still bound to the scratch
                 * page.  There are a number of places where the hardware
                 * apparently prefetches past the end of the object, and we've
                 * seen multiple hangs with the GPU head pointer stuck in a
                 * batchbuffer bound at the last page of the aperture.  One page
                 * should be enough to keep any prefetching inside of the
                 * aperture.
                 */
                i915_gem_do_init(dev, 0, mappable_size, gtt_size - PAGE_SIZE);
        }

        ret = i915_gem_init_hw(dev);
        DRM_UNLOCK(dev);
        if (ret != 0) {
                i915_gem_cleanup_aliasing_ppgtt(dev);
                return (ret);
        }

#if 0
        /* Try to set up FBC with a reasonable compressed buffer size */
        if (I915_HAS_FBC(dev) && i915_powersave) {
                int cfb_size;

                /* Leave 1M for line length buffer & misc. */

                /* Try to get a 32M buffer... */
                if (prealloc_size > (36*1024*1024))
                        cfb_size = 32*1024*1024;
                else /* fall back to 7/8 of the stolen space */
                        cfb_size = prealloc_size * 7 / 8;
                i915_setup_compression(dev, cfb_size);
        }
#endif

        /* Allow hardware batchbuffers unless told otherwise, but not for KMS. */
        if (!drm_core_check_feature(dev, DRIVER_MODESET))
                dev_priv->dri1.allow_batchbuffer = 1;
        return 0;
}

void
i915_gem_cleanup_ringbuffer(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv;
        int i;

        dev_priv = dev->dev_private;
        for (i = 0; i < I915_NUM_RINGS; i++)
                intel_cleanup_ring_buffer(&dev_priv->ring[i]);
}

int
i915_gem_entervt_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret;

        if (drm_core_check_feature(dev, DRIVER_MODESET))
                return 0;

        if (atomic_read(&dev_priv->mm.wedged)) {
                DRM_ERROR("Reenabling wedged hardware, good luck\n");
                atomic_set(&dev_priv->mm.wedged, 0);
        }

        DRM_LOCK(dev);
        dev_priv->mm.suspended = 0;

        ret = i915_gem_init_hw(dev);
        if (ret != 0) {
                DRM_UNLOCK(dev);
                return ret;
        }

        KASSERT(list_empty(&dev_priv->mm.active_list), ("active list"));
        DRM_UNLOCK(dev);

        ret = drm_irq_install(dev);
        if (ret)
                goto cleanup_ringbuffer;

        return 0;

cleanup_ringbuffer:
        DRM_LOCK(dev);
        i915_gem_cleanup_ringbuffer(dev);
        dev_priv->mm.suspended = 1;
        DRM_UNLOCK(dev);

        return ret;
}

int
i915_gem_leavevt_ioctl(struct drm_device *dev, void *data,
    struct drm_file *file_priv)
{

        if (drm_core_check_feature(dev, DRIVER_MODESET))
                return 0;

        drm_irq_uninstall(dev);
        return (i915_gem_idle(dev));
}

void
i915_gem_lastclose(struct drm_device *dev)
{
        int ret;

        if (drm_core_check_feature(dev, DRIVER_MODESET))
                return;

        ret = i915_gem_idle(dev);
        if (ret != 0)
                DRM_ERROR("failed to idle hardware: %d\n", ret);
}

static void
init_ring_lists(struct intel_ring_buffer *ring)
{

        INIT_LIST_HEAD(&ring->active_list);
        INIT_LIST_HEAD(&ring->request_list);
        INIT_LIST_HEAD(&ring->gpu_write_list);
}

void
i915_gem_load(struct drm_device *dev)
{
        int i;
        drm_i915_private_t *dev_priv = dev->dev_private;

        INIT_LIST_HEAD(&dev_priv->mm.active_list);
        INIT_LIST_HEAD(&dev_priv->mm.inactive_list);
        INIT_LIST_HEAD(&dev_priv->mm.fence_list);
        INIT_LIST_HEAD(&dev_priv->mm.gtt_list);
        for (i = 0; i < I915_NUM_RINGS; i++)
                init_ring_lists(&dev_priv->ring[i]);
        for (i = 0; i < I915_MAX_NUM_FENCES; i++)
                INIT_LIST_HEAD(&dev_priv->fence_regs[i].lru_list);
        INIT_DELAYED_WORK(&dev_priv->mm.retire_work,
                          i915_gem_retire_work_handler);
        init_completion(&dev_priv->error_completion);

        /* On GEN3 we really need to make sure the ARB C3 LP bit is set */
        if (IS_GEN3(dev)) {
                I915_WRITE(MI_ARB_STATE,
                           _MASKED_BIT_ENABLE(MI_ARB_C3_LP_WRITE_ENABLE));
        }

        dev_priv->relative_constants_mode = I915_EXEC_CONSTANTS_REL_GENERAL;

        /* Old X drivers will take 0-2 for front, back, depth buffers */
        if (!drm_core_check_feature(dev, DRIVER_MODESET))
                dev_priv->fence_reg_start = 3;

        if (INTEL_INFO(dev)->gen >= 4 || IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev))
                dev_priv->num_fence_regs = 16;
        else
                dev_priv->num_fence_regs = 8;

        /* Initialize fence registers to zero */
        i915_gem_reset_fences(dev);

        i915_gem_detect_bit_6_swizzle(dev);
        init_waitqueue_head(&dev_priv->pending_flip_queue);

        dev_priv->mm.interruptible = true;

#if 0
        dev_priv->mm.inactive_shrinker.shrink = i915_gem_inactive_shrink;
        dev_priv->mm.inactive_shrinker.seeks = DEFAULT_SEEKS;
        register_shrinker(&dev_priv->mm.inactive_shrinker);
#else
        dev_priv->mm.i915_lowmem = EVENTHANDLER_REGISTER(vm_lowmem,
            i915_gem_lowmem, dev, EVENTHANDLER_PRI_ANY);
#endif
}

static int
i915_gem_init_phys_object(struct drm_device *dev, int id, int size, int align)
{
        drm_i915_private_t *dev_priv;
        struct drm_i915_gem_phys_object *phys_obj;
        int ret;

        dev_priv = dev->dev_private;
        if (dev_priv->mm.phys_objs[id - 1] != NULL || size == 0)
                return (0);

        phys_obj = kmalloc(sizeof(struct drm_i915_gem_phys_object), DRM_I915_GEM,
            M_WAITOK | M_ZERO);

        phys_obj->id = id;

        phys_obj->handle = drm_pci_alloc(dev, size, align, ~0);
        if (phys_obj->handle == NULL) {
                ret = -ENOMEM;
                goto free_obj;
        }
        pmap_change_attr((vm_offset_t)phys_obj->handle->vaddr,
            size / PAGE_SIZE, PAT_WRITE_COMBINING);

        dev_priv->mm.phys_objs[id - 1] = phys_obj;

        return (0);

free_obj:
        drm_free(phys_obj, DRM_I915_GEM);
        return (ret);
}

static void
i915_gem_free_phys_object(struct drm_device *dev, int id)
{
        drm_i915_private_t *dev_priv;
        struct drm_i915_gem_phys_object *phys_obj;

        dev_priv = dev->dev_private;
        if (dev_priv->mm.phys_objs[id - 1] == NULL)
                return;

        phys_obj = dev_priv->mm.phys_objs[id - 1];
        if (phys_obj->cur_obj != NULL)
                i915_gem_detach_phys_object(dev, phys_obj->cur_obj);

        drm_pci_free(dev, phys_obj->handle);
        drm_free(phys_obj, DRM_I915_GEM);
        dev_priv->mm.phys_objs[id - 1] = NULL;
}

void
i915_gem_free_all_phys_object(struct drm_device *dev)
{
        int i;

        for (i = I915_GEM_PHYS_CURSOR_0; i <= I915_MAX_PHYS_OBJECT; i++)
                i915_gem_free_phys_object(dev, i);
}

void
i915_gem_detach_phys_object(struct drm_device *dev,
    struct drm_i915_gem_object *obj)
{
        vm_page_t m;
        struct sf_buf *sf;
        char *vaddr, *dst;
        int i, page_count;

        if (obj->phys_obj == NULL)
                return;
        vaddr = obj->phys_obj->handle->vaddr;

        page_count = obj->base.size / PAGE_SIZE;
        VM_OBJECT_LOCK(obj->base.vm_obj);
        for (i = 0; i < page_count; i++) {
                m = i915_gem_wire_page(obj->base.vm_obj, i);
                if (m == NULL)
                        continue; /* XXX */

                VM_OBJECT_UNLOCK(obj->base.vm_obj);
                sf = sf_buf_alloc(m);
                if (sf != NULL) {
                        dst = (char *)sf_buf_kva(sf);
                        memcpy(dst, vaddr + IDX_TO_OFF(i), PAGE_SIZE);
                        sf_buf_free(sf);
                }
                drm_clflush_pages(&m, 1);

                VM_OBJECT_LOCK(obj->base.vm_obj);
                vm_page_reference(m);
                vm_page_dirty(m);
                vm_page_busy_wait(m, FALSE, "i915gem");
                vm_page_unwire(m, 0);
                vm_page_wakeup(m);
                atomic_add_long(&i915_gem_wired_pages_cnt, -1);
        }
        VM_OBJECT_UNLOCK(obj->base.vm_obj);
        intel_gtt_chipset_flush();

        obj->phys_obj->cur_obj = NULL;
        obj->phys_obj = NULL;
}

int
i915_gem_attach_phys_object(struct drm_device *dev,
                            struct drm_i915_gem_object *obj,
                            int id,
                            int align)
{
        drm_i915_private_t *dev_priv;
        vm_page_t m;
        struct sf_buf *sf;
        char *dst, *src;
        int i, page_count, ret;

        if (id > I915_MAX_PHYS_OBJECT)
                return (-EINVAL);

        if (obj->phys_obj != NULL) {
                if (obj->phys_obj->id == id)
                        return (0);
                i915_gem_detach_phys_object(dev, obj);
        }

        dev_priv = dev->dev_private;
        if (dev_priv->mm.phys_objs[id - 1] == NULL) {
                ret = i915_gem_init_phys_object(dev, id, obj->base.size, align);
                if (ret != 0) {
                        DRM_ERROR("failed to init phys object %d size: %zu\n",
                                  id, obj->base.size);
                        return (ret);
                }
        }

        /* bind to the object */
        obj->phys_obj = dev_priv->mm.phys_objs[id - 1];
        obj->phys_obj->cur_obj = obj;

        page_count = obj->base.size / PAGE_SIZE;

        VM_OBJECT_LOCK(obj->base.vm_obj);
        ret = 0;
        for (i = 0; i < page_count; i++) {
                m = i915_gem_wire_page(obj->base.vm_obj, i);
                if (m == NULL) {
                        ret = -EIO;
                        break;
                }
                VM_OBJECT_UNLOCK(obj->base.vm_obj);
                sf = sf_buf_alloc(m);
                src = (char *)sf_buf_kva(sf);
                dst = (char *)obj->phys_obj->handle->vaddr + IDX_TO_OFF(i);
                memcpy(dst, src, PAGE_SIZE);
                sf_buf_free(sf);

                VM_OBJECT_LOCK(obj->base.vm_obj);

                vm_page_reference(m);
                vm_page_busy_wait(m, FALSE, "i915gem");
                vm_page_unwire(m, 0);
                vm_page_wakeup(m);
                atomic_add_long(&i915_gem_wired_pages_cnt, -1);
        }
        VM_OBJECT_UNLOCK(obj->base.vm_obj);

        return (0);
}

static int
i915_gem_phys_pwrite(struct drm_device *dev, struct drm_i915_gem_object *obj,
    uint64_t data_ptr, uint64_t offset, uint64_t size,
    struct drm_file *file_priv)
{
        char *user_data, *vaddr;
        int ret;

        vaddr = (char *)obj->phys_obj->handle->vaddr + offset;
        user_data = (char *)(uintptr_t)data_ptr;

        if (copyin_nofault(user_data, vaddr, size) != 0) {
                /* The physical object once assigned is fixed for the lifetime
                 * of the obj, so we can safely drop the lock and continue
                 * to access vaddr.
                 */
                DRM_UNLOCK(dev);
                ret = -copyin(user_data, vaddr, size);
                DRM_LOCK(dev);
                if (ret != 0)
                        return (ret);
        }

        intel_gtt_chipset_flush();
        return (0);
}

void
i915_gem_release(struct drm_device *dev, struct drm_file *file)
{
        struct drm_i915_file_private *file_priv;
        struct drm_i915_gem_request *request;

        file_priv = file->driver_priv;

        /* Clean up our request list when the client is going away, so that
         * later retire_requests won't dereference our soon-to-be-gone
         * file_priv.
         */
        spin_lock(&file_priv->mm.lock);
        while (!list_empty(&file_priv->mm.request_list)) {
                request = list_first_entry(&file_priv->mm.request_list,
                                           struct drm_i915_gem_request,
                                           client_list);
                list_del(&request->client_list);
                request->file_priv = NULL;
        }
        spin_unlock(&file_priv->mm.lock);
}

static int
i915_gem_swap_io(struct drm_device *dev, struct drm_i915_gem_object *obj,
    uint64_t data_ptr, uint64_t size, uint64_t offset, enum uio_rw rw,
    struct drm_file *file)
{
        vm_object_t vm_obj;
        vm_page_t m;
        struct sf_buf *sf;
        vm_offset_t mkva;
        vm_pindex_t obj_pi;
        int cnt, do_bit17_swizzling, length, obj_po, ret, swizzled_po;

        if (obj->gtt_offset != 0 && rw == UIO_READ)
                do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);
        else
                do_bit17_swizzling = 0;

        obj->dirty = 1;
        vm_obj = obj->base.vm_obj;
        ret = 0;

        VM_OBJECT_LOCK(vm_obj);
        vm_object_pip_add(vm_obj, 1);
        while (size > 0) {
                obj_pi = OFF_TO_IDX(offset);
                obj_po = offset & PAGE_MASK;

                m = i915_gem_wire_page(vm_obj, obj_pi);
                VM_OBJECT_UNLOCK(vm_obj);

                sf = sf_buf_alloc(m);
                mkva = sf_buf_kva(sf);
                length = min(size, PAGE_SIZE - obj_po);
                while (length > 0) {
                        if (do_bit17_swizzling &&
                            (VM_PAGE_TO_PHYS(m) & (1 << 17)) != 0) {
                                cnt = roundup2(obj_po + 1, 64);
                                cnt = min(cnt - obj_po, length);
                                swizzled_po = obj_po ^ 64;
                        } else {
                                cnt = length;
                                swizzled_po = obj_po;
                        }
                        if (rw == UIO_READ)
                                ret = -copyout_nofault(
                                    (char *)mkva + swizzled_po,
                                    (void *)(uintptr_t)data_ptr, cnt);
                        else
                                ret = -copyin_nofault(
                                    (void *)(uintptr_t)data_ptr,
                                    (char *)mkva + swizzled_po, cnt);
                        if (ret != 0)
                                break;
                        data_ptr += cnt;
                        size -= cnt;
                        length -= cnt;
                        offset += cnt;
                        obj_po += cnt;
                }
                sf_buf_free(sf);
                VM_OBJECT_LOCK(vm_obj);
                if (rw == UIO_WRITE)
                        vm_page_dirty(m);
                vm_page_reference(m);
                vm_page_busy_wait(m, FALSE, "i915gem");
                vm_page_unwire(m, 1);
                vm_page_wakeup(m);
                atomic_add_long(&i915_gem_wired_pages_cnt, -1);

                if (ret != 0)
                        break;
        }
        vm_object_pip_wakeup(vm_obj);
        VM_OBJECT_UNLOCK(vm_obj);

        return (ret);
}

static int
i915_gem_gtt_write(struct drm_device *dev, struct drm_i915_gem_object *obj,
    uint64_t data_ptr, uint64_t size, uint64_t offset, struct drm_file *file)
{
        vm_offset_t mkva;
        int ret;

        /*
         * Pass the unaligned physical address and size to pmap_mapdev_attr()
         * so it can properly calculate whether an extra page needs to be
         * mapped or not to cover the requested range.  The function will
         * add the page offset into the returned mkva for us.
         */
        mkva = (vm_offset_t)pmap_mapdev_attr(dev->agp->base + obj->gtt_offset +
            offset, size, PAT_WRITE_COMBINING);
        ret = -copyin_nofault((void *)(uintptr_t)data_ptr, (char *)mkva, size);
        pmap_unmapdev(mkva, size);
        return (ret);
}

static int
i915_gem_obj_io(struct drm_device *dev, uint32_t handle, uint64_t data_ptr,
    uint64_t size, uint64_t offset, enum uio_rw rw, struct drm_file *file)
{
        struct drm_i915_gem_object *obj;
        vm_page_t *ma;
        vm_offset_t start, end;
        int npages, ret;

        if (size == 0)
                return (0);
        start = trunc_page(data_ptr);
        end = round_page(data_ptr + size);
        npages = howmany(end - start, PAGE_SIZE);
        ma = kmalloc(npages * sizeof(vm_page_t), DRM_I915_GEM, M_WAITOK |
            M_ZERO);
        npages = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
            (vm_offset_t)data_ptr, size,
            (rw == UIO_READ ? VM_PROT_WRITE : 0 ) | VM_PROT_READ, ma, npages);
        if (npages == -1) {
                ret = -EFAULT;
                goto free_ma;
        }

        ret = i915_mutex_lock_interruptible(dev);
        if (ret != 0)
                goto unlocked;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }
        if (offset > obj->base.size || size > obj->base.size - offset) {
                ret = -EINVAL;
                goto out;
        }

        if (rw == UIO_READ) {
                ret = i915_gem_swap_io(dev, obj, data_ptr, size, offset,
                    UIO_READ, file);
        } else {
                if (obj->phys_obj) {
                        ret = i915_gem_phys_pwrite(dev, obj, data_ptr, offset,
                            size, file);
                } else if (obj->gtt_space &&
                    obj->base.write_domain != I915_GEM_DOMAIN_CPU) {
                        ret = i915_gem_object_pin(obj, 0, true);
                        if (ret != 0)
                                goto out;
                        ret = i915_gem_object_set_to_gtt_domain(obj, true);
                        if (ret != 0)
                                goto out_unpin;
                        ret = i915_gem_object_put_fence(obj);
                        if (ret != 0)
                                goto out_unpin;
                        ret = i915_gem_gtt_write(dev, obj, data_ptr, size,
                            offset, file);
out_unpin:
                        i915_gem_object_unpin(obj);
                } else {
                        ret = i915_gem_object_set_to_cpu_domain(obj, true);
                        if (ret != 0)
                                goto out;
                        ret = i915_gem_swap_io(dev, obj, data_ptr, size, offset,
                            UIO_WRITE, file);
                }
        }
out:
        drm_gem_object_unreference(&obj->base);
unlock:
        DRM_UNLOCK(dev);
unlocked:
        vm_page_unhold_pages(ma, npages);
free_ma:
        drm_free(ma, DRM_I915_GEM);
        return (ret);
}

static int
i915_gem_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
    vm_ooffset_t foff, struct ucred *cred, u_short *color)
{

        *color = 0; /* XXXKIB */
        return (0);
}

int i915_intr_pf;

static int
i915_gem_pager_fault(vm_object_t vm_obj, vm_ooffset_t offset, int prot,
    vm_page_t *mres)
{
        struct drm_gem_object *gem_obj;
        struct drm_i915_gem_object *obj;
        struct drm_device *dev;
        drm_i915_private_t *dev_priv;
        vm_page_t m, oldm;
        int cause, ret;
        bool write;

        gem_obj = vm_obj->handle;
        obj = to_intel_bo(gem_obj);
        dev = obj->base.dev;
        dev_priv = dev->dev_private;
#if 0
        write = (prot & VM_PROT_WRITE) != 0;
#else
        write = true;
#endif
        vm_object_pip_add(vm_obj, 1);

        /*
         * Remove the placeholder page inserted by vm_fault() from the
         * object before dropping the object lock. If
         * i915_gem_release_mmap() is active in parallel on this gem
         * object, then it owns the drm device sx and might find the
         * placeholder already. Then, since the page is busy,
         * i915_gem_release_mmap() sleeps waiting for the busy state
         * of the page cleared. We will be not able to acquire drm
         * device lock until i915_gem_release_mmap() is able to make a
         * progress.
         */
        if (*mres != NULL) {
                oldm = *mres;
                vm_page_remove(oldm);
                *mres = NULL;
        } else
                oldm = NULL;
retry:
        VM_OBJECT_UNLOCK(vm_obj);
unlocked_vmobj:
        cause = ret = 0;
        m = NULL;

        if (i915_intr_pf) {
                ret = i915_mutex_lock_interruptible(dev);
                if (ret != 0) {
                        cause = 10;
                        goto out;
                }
        } else
                DRM_LOCK(dev);

        /*
         * Since the object lock was dropped, other thread might have
         * faulted on the same GTT address and instantiated the
         * mapping for the page.  Recheck.
         */
        VM_OBJECT_LOCK(vm_obj);
        m = vm_page_lookup(vm_obj, OFF_TO_IDX(offset));
        if (m != NULL) {
                if ((m->flags & PG_BUSY) != 0) {
                        DRM_UNLOCK(dev);
#if 0 /* XXX */
                        vm_page_sleep(m, "915pee");
#endif
                        goto retry;
                }
                goto have_page;
        } else
                VM_OBJECT_UNLOCK(vm_obj);

        /* Now bind it into the GTT if needed */
        if (!obj->map_and_fenceable) {
                ret = i915_gem_object_unbind(obj);
                if (ret != 0) {
                        cause = 20;
                        goto unlock;
                }
        }
        if (!obj->gtt_space) {
                ret = i915_gem_object_bind_to_gtt(obj, 0, true);
                if (ret != 0) {
                        cause = 30;
                        goto unlock;
                }

                ret = i915_gem_object_set_to_gtt_domain(obj, write);
                if (ret != 0) {
                        cause = 40;
                        goto unlock;
                }
        }

        if (obj->tiling_mode == I915_TILING_NONE)
                ret = i915_gem_object_put_fence(obj);
        else
                ret = i915_gem_object_get_fence(obj);
        if (ret != 0) {
                cause = 50;
                goto unlock;
        }

        if (i915_gem_object_is_inactive(obj))
                list_move_tail(&obj->mm_list, &dev_priv->mm.inactive_list);

        obj->fault_mappable = true;
        VM_OBJECT_LOCK(vm_obj);
        m = vm_phys_fictitious_to_vm_page(dev->agp->base + obj->gtt_offset +
            offset);
        if (m == NULL) {
                cause = 60;
                ret = -EFAULT;
                goto unlock;
        }
        KASSERT((m->flags & PG_FICTITIOUS) != 0,
            ("not fictitious %p", m));
        KASSERT(m->wire_count == 1, ("wire_count not 1 %p", m));

        if ((m->flags & PG_BUSY) != 0) {
                DRM_UNLOCK(dev);
#if 0 /* XXX */
                vm_page_sleep(m, "915pbs");
#endif
                goto retry;
        }
        m->valid = VM_PAGE_BITS_ALL;
        vm_page_insert(m, vm_obj, OFF_TO_IDX(offset));
have_page:
        *mres = m;
        vm_page_busy_try(m, false);

        DRM_UNLOCK(dev);
        if (oldm != NULL) {
                vm_page_free(oldm);
        }
        vm_object_pip_wakeup(vm_obj);
        return (VM_PAGER_OK);

unlock:
        DRM_UNLOCK(dev);
out:
        KASSERT(ret != 0, ("i915_gem_pager_fault: wrong return"));
        if (ret == -EAGAIN || ret == -EIO || ret == -EINTR) {
                goto unlocked_vmobj;
        }
        VM_OBJECT_LOCK(vm_obj);
        vm_object_pip_wakeup(vm_obj);
        return (VM_PAGER_ERROR);
}

static void
i915_gem_pager_dtor(void *handle)
{
        struct drm_gem_object *obj;
        struct drm_device *dev;

        obj = handle;
        dev = obj->dev;

        DRM_LOCK(dev);
        drm_gem_free_mmap_offset(obj);
        i915_gem_release_mmap(to_intel_bo(obj));
        drm_gem_object_unreference(obj);
        DRM_UNLOCK(dev);
}

struct cdev_pager_ops i915_gem_pager_ops = {
        .cdev_pg_fault  = i915_gem_pager_fault,
        .cdev_pg_ctor   = i915_gem_pager_ctor,
        .cdev_pg_dtor   = i915_gem_pager_dtor
};

#define GEM_PARANOID_CHECK_GTT 0
#if GEM_PARANOID_CHECK_GTT
static void
i915_gem_assert_pages_not_mapped(struct drm_device *dev, vm_page_t *ma,
    int page_count)
{
        struct drm_i915_private *dev_priv;
        vm_paddr_t pa;
        unsigned long start, end;
        u_int i;
        int j;

        dev_priv = dev->dev_private;
        start = OFF_TO_IDX(dev_priv->mm.gtt_start);
        end = OFF_TO_IDX(dev_priv->mm.gtt_end);
        for (i = start; i < end; i++) {
                pa = intel_gtt_read_pte_paddr(i);
                for (j = 0; j < page_count; j++) {
                        if (pa == VM_PAGE_TO_PHYS(ma[j])) {
                                panic("Page %p in GTT pte index %d pte %x",
                                    ma[i], i, intel_gtt_read_pte(i));
                        }
                }
        }
}
#endif

static void
i915_gem_process_flushing_list(struct intel_ring_buffer *ring,
    uint32_t flush_domains)
{
        struct drm_i915_gem_object *obj, *next;
        uint32_t old_write_domain;

        list_for_each_entry_safe(obj, next, &ring->gpu_write_list,
            gpu_write_list) {
                if (obj->base.write_domain & flush_domains) {
                        old_write_domain = obj->base.write_domain;
                        obj->base.write_domain = 0;
                        list_del_init(&obj->gpu_write_list);
                        i915_gem_object_move_to_active(obj, ring);
                }
        }
}

#define VM_OBJECT_LOCK_ASSERT_OWNED(object)

static vm_page_t
i915_gem_wire_page(vm_object_t object, vm_pindex_t pindex)
{
        vm_page_t m;
        int rv;

        VM_OBJECT_LOCK_ASSERT_OWNED(object);
        m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
        if (m->valid != VM_PAGE_BITS_ALL) {
                if (vm_pager_has_page(object, pindex)) {
                        rv = vm_pager_get_page(object, &m, 1);
                        m = vm_page_lookup(object, pindex);
                        if (m == NULL)
                                return (NULL);
                        if (rv != VM_PAGER_OK) {
                                vm_page_free(m);
                                return (NULL);
                        }
                } else {
                        pmap_zero_page(VM_PAGE_TO_PHYS(m));
                        m->valid = VM_PAGE_BITS_ALL;
                        m->dirty = 0;
                }
        }
        vm_page_wire(m);
        vm_page_wakeup(m);
        atomic_add_long(&i915_gem_wired_pages_cnt, 1);
        return (m);
}

int
i915_gem_flush_ring(struct intel_ring_buffer *ring, uint32_t invalidate_domains,
    uint32_t flush_domains)
{
        int ret;

        if (((invalidate_domains | flush_domains) & I915_GEM_GPU_DOMAINS) == 0)
                return 0;

        ret = ring->flush(ring, invalidate_domains, flush_domains);
        if (ret)
                return ret;

        if (flush_domains & I915_GEM_GPU_DOMAINS)
                i915_gem_process_flushing_list(ring, flush_domains);
        return 0;
}

static int
i915_gpu_is_active(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;

        return !list_empty(&dev_priv->mm.active_list);
}

static void
i915_gem_lowmem(void *arg)
{
        struct drm_device *dev;
        struct drm_i915_private *dev_priv;
        struct drm_i915_gem_object *obj, *next;
        int cnt, cnt_fail, cnt_total;

        dev = arg;
        dev_priv = dev->dev_private;

        if (lockmgr(&dev->dev_struct_lock, LK_EXCLUSIVE|LK_NOWAIT))
                return;

rescan:
        /* first scan for clean buffers */
        i915_gem_retire_requests(dev);

        cnt_total = cnt_fail = cnt = 0;

        list_for_each_entry_safe(obj, next, &dev_priv->mm.inactive_list,
            mm_list) {
                if (i915_gem_object_is_purgeable(obj)) {
                        if (i915_gem_object_unbind(obj) != 0)
                                cnt_total++;
                } else
                        cnt_total++;
        }

        /* second pass, evict/count anything still on the inactive list */
        list_for_each_entry_safe(obj, next, &dev_priv->mm.inactive_list,
            mm_list) {
                if (i915_gem_object_unbind(obj) == 0)
                        cnt++;
                else
                        cnt_fail++;
        }

        if (cnt_fail > cnt_total / 100 && i915_gpu_is_active(dev)) {
                /*
                 * We are desperate for pages, so as a last resort, wait
                 * for the GPU to finish and discard whatever we can.
                 * This has a dramatic impact to reduce the number of
                 * OOM-killer events whilst running the GPU aggressively.
                 */
                if (i915_gpu_idle(dev) == 0)
                        goto rescan;
        }
        DRM_UNLOCK(dev);
}

void
i915_gem_unload(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv;

        dev_priv = dev->dev_private;
        EVENTHANDLER_DEREGISTER(vm_lowmem, dev_priv->mm.i915_lowmem);
}