[PATCH v4 13/15] scsi: ufs: add missing memory barriers

From	Yaniv Gardi <ygardi@codeaurora.org>
Newsgroups	linux.kernel
Subject	[PATCH v4 13/15] scsi: ufs: add missing memory barriers
Date	2015-10-25 16:00 +0100
Message-ID	<qnuW7-4fF-65@gated-at.bofh.it> (permalink)
References	<qnuW5-4fF-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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 24a879d..14bebc5 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -402,11 +402,9 @@ 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;
 }
 
 /**
@@ -2727,7 +2725,7 @@ 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
@@ -2757,8 +2755,13 @@ 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))) {
@@ -3921,7 +3924,13 @@ 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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Thread

[PATCH v4 00/15] Big fixes, retries, handle a race condition Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 08/15] scsi: ufs: add retries to dme_peer get and set attribute Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 04/15] scsi: ufs: clear outstanding_request bit in case query timeout Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 13/15] scsi: ufs: add missing memory barriers Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 15/15] scsi: ufs: add wrapper for retrying sending query attribute Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 06/15] scsi: ufs: avoid exception event handler racing with PM callbacks Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 10/15] scsi: ufs: fix error recovery after the hibern8 exit failure Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 03/15] scsi: ufs: verify command tag validity Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 09/15] scsi: ufs: add retries for hibern8 enter Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 14/15] scsi: ufs: commit descriptors before setting the doorbell Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 05/15] scsi: ufs: increase fDeviceInit query response timeout Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 02/15] scsi: ufs: clear fields UTRD, UPIU req and rsp before new transfers Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:00 +0100
  [PATCH v4 01/15] scsi: ufs: clear UTRD, UPIU req and rsp before new transfers Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:10 +0100
  [PATCH v4 07/15] scsi: ufs: set REQUEST_SENSE command size to 18 bytes Yaniv Gardi <ygardi@codeaurora.org> - 2015-10-25 16:10 +0100

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