From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Fri, 17 Jun 2011 02:45:48 +0000 (-0700)
Subject: kernel - Add AHCI workaround for Intel mobo / Intel SSD probing bug
X-Git-Tag: v2.12.0~451
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/f2dba7003b2add226b3999a41a99fd278cc5a26f

kernel - Add AHCI workaround for Intel mobo / Intel SSD probing bug

* On cold boot Intel SSDs for some reason seem to fail to initialize on
  the first attempt.  The AHCI port winds up getting stuck in BSY mode.
  Adjusting timeouts fails to solve the problem.  Ignoring the BSY state
  does solve the problem but is undesireable.

* Retry the initialization sequence once if a stuck BSY is detected
  as a workaround.  This appears to properly detect the SSD on the second
  attempt.

* Add a delay after clearing the power control state before starting the
  COMINIT sequence.  This solves no known issues but is probably a good
  idea.
---

diff --git a/sys/dev/disk/ahci/ahci.c b/sys/dev/disk/ahci/ahci.c
index 6ce365d40c..9c1e90924c 100644
--- a/sys/dev/disk/ahci/ahci.c
+++ b/sys/dev/disk/ahci/ahci.c
@@ -1358,6 +1358,7 @@ ahci_comreset(struct ahci_port *ap, int *pmdetectp)
 	u_int32_t r;
 	int error;
 	int loop;
+	int retries = 0;
 
 	/*
 	 * Idle the port,
@@ -1392,7 +1393,15 @@ ahci_comreset(struct ahci_port *ap, int *pmdetectp)
 	r = AHCI_PREG_SCTL_IPM_DISABLED |
 	    AHCI_PREG_SCTL_SPM_DISABLED;
 	ahci_pwrite(ap, AHCI_PREG_SCTL, r);
-	ahci_os_sleep(10);
+
+retry:
+	/*
+	 * Give the new power management state time to settle, then clear
+	 * pending status.
+	 */
+	ahci_os_sleep(1000);
+	ahci_flush_tfd(ap);
+	ahci_pwrite(ap, AHCI_PREG_SERR, -1);
 
 	/*
 	 * Start transmitting COMRESET.  The spec says that COMRESET must
@@ -1423,14 +1432,14 @@ ahci_comreset(struct ahci_port *ap, int *pmdetectp)
 	}
 	ahci_pwrite(ap, AHCI_PREG_SCTL, r);
 	ahci_os_sleep(1000);
-	r &= ~AHCI_PREG_SCTL_SPD;
 
 	ap->ap_flags &= ~AP_F_HARSH_REINIT;
 
 	/*
 	 * Only SERR_DIAG_X needs to be cleared for TFD updates, but
 	 * since we are hard-resetting the port we might as well clear
-	 * the whole enchillada.
+	 * the whole enchillada.  Also be sure to clear any spurious BSY
+	 * prior to clearing INIT.
 	 *
 	 * Wait 1 whole second after clearing INIT before checking
 	 * the device detection bits in an attempt to work around chipsets
@@ -1438,8 +1447,10 @@ ahci_comreset(struct ahci_port *ap, int *pmdetectp)
 	 */
 	ahci_flush_tfd(ap);
 	ahci_pwrite(ap, AHCI_PREG_SERR, -1);
+/*	ahci_port_clo(ap);*/
 	ahci_os_sleep(10);
 
+	r &= ~AHCI_PREG_SCTL_SPD;
 	r &= ~AHCI_PREG_SCTL_DET_INIT;
 	r |= AHCI_PREG_SCTL_DET_NONE;
 	ahci_pwrite(ap, AHCI_PREG_SCTL, r);
@@ -1494,10 +1505,25 @@ ahci_comreset(struct ahci_port *ap, int *pmdetectp)
 	 *
 	 * NOTE: A port multiplier may or may not clear BSY here,
 	 *	 depending on what is sitting in target 0 behind it.
+	 *
+	 * NOTE: Intel SSDs seem to have compatibility problems with Intel
+	 *	 mobo's on cold boots and may leave BSY set.  A single
+	 *	 retry works around the problem.  This is definitely a bug
+	 *	 with the mobo and/or the SSD and does not appear to occur
+	 *	 with other devices connected to the same port.
 	 */
 	ahci_flush_tfd(ap);
-	if (ahci_pwait_clr_to(ap, 3000, AHCI_PREG_TFD,
+	if (ahci_pwait_clr_to(ap, 8000, AHCI_PREG_TFD,
 			    AHCI_PREG_TFD_STS_BSY | AHCI_PREG_TFD_STS_DRQ)) {
+		kprintf("%s: Device BUSY: %b\n",
+			PORTNAME(ap),
+			ahci_pread(ap, AHCI_PREG_TFD),
+				AHCI_PFMT_TFD_STS);
+		if (retries == 0) {
+			kprintf("%s: Retrying\n", PORTNAME(ap));
+			retries = 1;
+			goto retry;
+		}
 		error = EBUSY;
 	} else {
 		error = 0;