2 * Copyright (c) 2014 Samsung Electronics Co., Ltd
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5 * copy of this software and associated documentation files (the "Software"),
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9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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21 * DEALINGS IN THE SOFTWARE.
24 #include <linux/err.h>
25 #include <linux/module.h>
26 #include <linux/mutex.h>
28 #include <drm/drm_bridge.h>
29 #include <drm/drm_encoder.h>
31 #include "drm_crtc_internal.h"
36 * struct &drm_bridge represents a device that hangs on to an encoder. These are
37 * handy when a regular &drm_encoder entity isn't enough to represent the entire
40 * A bridge is always attached to a single &drm_encoder at a time, but can be
41 * either connected to it directly, or through an intermediate bridge::
43 * encoder ---> bridge B ---> bridge A
45 * Here, the output of the encoder feeds to bridge B, and that furthers feeds to
48 * The driver using the bridge is responsible to make the associations between
49 * the encoder and bridges. Once these links are made, the bridges will
50 * participate along with encoder functions to perform mode_set/enable/disable
51 * through the ops provided in &drm_bridge_funcs.
53 * drm_bridge, like drm_panel, aren't drm_mode_object entities like planes,
54 * CRTCs, encoders or connectors and hence are not visible to userspace. They
55 * just provide additional hooks to get the desired output at the end of the
58 * Bridges can also be chained up using the next pointer in struct &drm_bridge.
60 * Both legacy CRTC helpers and the new atomic modeset helpers support bridges.
63 static DEFINE_MUTEX(bridge_lock);
64 static LINUX_LIST_HEAD(bridge_list);
67 * drm_bridge_add - add the given bridge to the global bridge list
69 * @bridge: bridge control structure
72 * Unconditionally returns Zero.
74 int drm_bridge_add(struct drm_bridge *bridge)
76 mutex_lock(&bridge_lock);
77 list_add_tail(&bridge->list, &bridge_list);
78 mutex_unlock(&bridge_lock);
82 EXPORT_SYMBOL(drm_bridge_add);
85 * drm_bridge_remove - remove the given bridge from the global bridge list
87 * @bridge: bridge control structure
89 void drm_bridge_remove(struct drm_bridge *bridge)
91 mutex_lock(&bridge_lock);
92 list_del_init(&bridge->list);
93 mutex_unlock(&bridge_lock);
95 EXPORT_SYMBOL(drm_bridge_remove);
98 * drm_bridge_attach - attach the bridge to an encoder's chain
100 * @encoder: DRM encoder
101 * @bridge: bridge to attach
102 * @previous: previous bridge in the chain (optional)
104 * Called by a kms driver to link the bridge to an encoder's chain. The previous
105 * argument specifies the previous bridge in the chain. If NULL, the bridge is
106 * linked directly at the encoder's output. Otherwise it is linked at the
107 * previous bridge's output.
109 * If non-NULL the previous bridge must be already attached by a call to this
113 * Zero on success, error code on failure
115 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
116 struct drm_bridge *previous)
120 if (!encoder || !bridge)
123 if (previous && (!previous->dev || previous->encoder != encoder))
129 bridge->dev = encoder->dev;
130 bridge->encoder = encoder;
132 if (bridge->funcs->attach) {
133 ret = bridge->funcs->attach(bridge);
136 bridge->encoder = NULL;
142 previous->next = bridge;
144 encoder->bridge = bridge;
148 EXPORT_SYMBOL(drm_bridge_attach);
150 void drm_bridge_detach(struct drm_bridge *bridge)
152 if (WARN_ON(!bridge))
155 if (WARN_ON(!bridge->dev))
158 if (bridge->funcs->detach)
159 bridge->funcs->detach(bridge);
165 * DOC: bridge callbacks
167 * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
168 * internals (atomic and CRTC helpers) use the helpers defined in drm_bridge.c
169 * These helpers call a specific &drm_bridge_funcs op for all the bridges
170 * during encoder configuration.
172 * For detailed specification of the bridge callbacks see &drm_bridge_funcs.
176 * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the
178 * @bridge: bridge control structure
179 * @mode: desired mode to be set for the bridge
180 * @adjusted_mode: updated mode that works for this bridge
182 * Calls ->mode_fixup() &drm_bridge_funcs op for all the bridges in the
183 * encoder chain, starting from the first bridge to the last.
185 * Note: the bridge passed should be the one closest to the encoder
188 * true on success, false on failure
190 bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
191 const struct drm_display_mode *mode,
192 struct drm_display_mode *adjusted_mode)
199 if (bridge->funcs->mode_fixup)
200 ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode);
202 ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode);
206 EXPORT_SYMBOL(drm_bridge_mode_fixup);
209 * drm_bridge_disable - calls ->disable() &drm_bridge_funcs op for all
210 * bridges in the encoder chain.
211 * @bridge: bridge control structure
213 * Calls ->disable() &drm_bridge_funcs op for all the bridges in the encoder
214 * chain, starting from the last bridge to the first. These are called before
215 * calling the encoder's prepare op.
217 * Note: the bridge passed should be the one closest to the encoder
219 void drm_bridge_disable(struct drm_bridge *bridge)
224 drm_bridge_disable(bridge->next);
226 if (bridge->funcs->disable)
227 bridge->funcs->disable(bridge);
229 EXPORT_SYMBOL(drm_bridge_disable);
232 * drm_bridge_post_disable - calls ->post_disable() &drm_bridge_funcs op for
233 * all bridges in the encoder chain.
234 * @bridge: bridge control structure
236 * Calls ->post_disable() &drm_bridge_funcs op for all the bridges in the
237 * encoder chain, starting from the first bridge to the last. These are called
238 * after completing the encoder's prepare op.
240 * Note: the bridge passed should be the one closest to the encoder
242 void drm_bridge_post_disable(struct drm_bridge *bridge)
247 if (bridge->funcs->post_disable)
248 bridge->funcs->post_disable(bridge);
250 drm_bridge_post_disable(bridge->next);
252 EXPORT_SYMBOL(drm_bridge_post_disable);
255 * drm_bridge_mode_set - set proposed mode for all bridges in the
257 * @bridge: bridge control structure
258 * @mode: desired mode to be set for the bridge
259 * @adjusted_mode: updated mode that works for this bridge
261 * Calls ->mode_set() &drm_bridge_funcs op for all the bridges in the
262 * encoder chain, starting from the first bridge to the last.
264 * Note: the bridge passed should be the one closest to the encoder
266 void drm_bridge_mode_set(struct drm_bridge *bridge,
267 struct drm_display_mode *mode,
268 struct drm_display_mode *adjusted_mode)
273 if (bridge->funcs->mode_set)
274 bridge->funcs->mode_set(bridge, mode, adjusted_mode);
276 drm_bridge_mode_set(bridge->next, mode, adjusted_mode);
278 EXPORT_SYMBOL(drm_bridge_mode_set);
281 * drm_bridge_pre_enable - calls ->pre_enable() &drm_bridge_funcs op for all
282 * bridges in the encoder chain.
283 * @bridge: bridge control structure
285 * Calls ->pre_enable() &drm_bridge_funcs op for all the bridges in the encoder
286 * chain, starting from the last bridge to the first. These are called
287 * before calling the encoder's commit op.
289 * Note: the bridge passed should be the one closest to the encoder
291 void drm_bridge_pre_enable(struct drm_bridge *bridge)
296 drm_bridge_pre_enable(bridge->next);
298 if (bridge->funcs->pre_enable)
299 bridge->funcs->pre_enable(bridge);
301 EXPORT_SYMBOL(drm_bridge_pre_enable);
304 * drm_bridge_enable - calls ->enable() &drm_bridge_funcs op for all bridges
305 * in the encoder chain.
306 * @bridge: bridge control structure
308 * Calls ->enable() &drm_bridge_funcs op for all the bridges in the encoder
309 * chain, starting from the first bridge to the last. These are called
310 * after completing the encoder's commit op.
312 * Note that the bridge passed should be the one closest to the encoder
314 void drm_bridge_enable(struct drm_bridge *bridge)
319 if (bridge->funcs->enable)
320 bridge->funcs->enable(bridge);
322 drm_bridge_enable(bridge->next);
324 EXPORT_SYMBOL(drm_bridge_enable);
328 * of_drm_find_bridge - find the bridge corresponding to the device node in
329 * the global bridge list
334 * drm_bridge control struct on success, NULL on failure
336 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
338 struct drm_bridge *bridge;
340 mutex_lock(&bridge_lock);
342 list_for_each_entry(bridge, &bridge_list, list) {
343 if (bridge->of_node == np) {
344 mutex_unlock(&bridge_lock);
349 mutex_unlock(&bridge_lock);
352 EXPORT_SYMBOL(of_drm_find_bridge);
355 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
356 MODULE_DESCRIPTION("DRM bridge infrastructure");