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[PATCH v2 13/15] scsi: ufs: add missing memory barriers

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Performing several writes to UFS host controller registers has
no gurrantee of ordering, so we must make sure register writes
to setup request list base address etc. are performed before the
run/stop register is enabled.
In addition, when setting up a task request, we must make sure
the updating of descriptors takes places before ringing the
doorbell, similarly to setting up a transfer request.

Signed-off-by: Gilad Broner <gbroner@codeaurora.org>
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index fc2a52d..298511a 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -401,11 +401,9 @@ static inline int ufshcd_get_lists_status(u32 reg)
 	 *  1		UTRLRDY
 	 *  2		UTMRLRDY
 	 *  3		UCRDY
-	 *  4		HEI
-	 *  5		DEI
-	 * 6-7		reserved
+	 * 4-7		reserved
 	 */
-	return (((reg) & (0xFF)) >> 1) ^ (0x07);
+	return ((reg & 0xFF) >> 1) ^ 0x07;
 }
 
 /**
@@ -2726,7 +2724,7 @@ out:
  * To bring UFS host controller to operational state,
  * 1. Enable required interrupts
  * 2. Configure interrupt aggregation
- * 3. Program UTRL and UTMRL base addres
+ * 3. Program UTRL and UTMRL base address
  * 4. Configure run-stop-registers
  *
  * Returns 0 on success, non-zero value on failure
@@ -2756,8 +2754,13 @@ static int ufshcd_make_hba_operational(struct ufs_hba *hba)
 			REG_UTP_TASK_REQ_LIST_BASE_H);
 
 	/*
+	 * Make sure base address and interrupt setup are updated before
+	 * enabling the run/stop registers below.
+	 */
+	wmb();
+
+	/*
 	 * UCRDY, UTMRLDY and UTRLRDY bits must be 1
-	 * DEI, HEI bits must be 0
 	 */
 	reg = ufshcd_readl(hba, REG_CONTROLLER_STATUS);
 	if (!(ufshcd_get_lists_status(reg))) {
@@ -3920,7 +3923,13 @@ static int ufshcd_issue_tm_cmd(struct ufs_hba *hba, int lun_id, int task_id,
 
 	/* send command to the controller */
 	__set_bit(free_slot, &hba->outstanding_tasks);
+
+	/* Make sure descriptors are ready before ringing the task doorbell */
+	wmb();
+
 	ufshcd_writel(hba, 1 << free_slot, REG_UTP_TASK_REQ_DOOR_BELL);
+	/* Make sure that doorbell is committed immediately */
+	wmb();
 
 	spin_unlock_irqrestore(host->host_lock, flags);
 
-- 
1.8.5.2

-- 
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[PATCH v2 00/15] Big fixes, retries, handle a race condition Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200
  [PATCH v2 12/15] scsi: ufs: reduce the interrupts for power mode change requests Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200
  [PATCH v2 14/15] scsi: ufs: commit descriptors before setting the doorbell Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200
  [PATCH v2 11/15] scsi: ufs: retry failed query flag requests Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200
  [PATCH v2 01/15] scsi: ufs: clear UTRD, UPIU req and rsp before new transfers Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200
  [PATCH v2 06/15] scsi: ufs: avoid exception event handler racing with PM callbacks Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200
  [PATCH v2 08/15] scsi: ufs: add retries to dme_peer get and set attribute Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200
  [PATCH v2 05/15] scsi: ufs: increase fDeviceInit query response timeout Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200
  [PATCH v2 13/15] scsi: ufs: add missing memory barriers Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200
  [PATCH v2 03/15] scsi: ufs: verify command tag validity Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200
  [PATCH v2 10/15] scsi: ufs: fix error recovery after the hibern8 exit failure Yaniv Gardi <ygardi@codeaurora.org> - 2015-08-27 14:50 +0200

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