[PATCH v6 14/15] scsi: ufs: commit descriptors before setting the doorbell

[Yaniv Gardi]

Add a write memory barrier to make sure descriptors prepared are actually
written to memory before ringing the doorbell. We have also added the
write memory barrier after ringing the doorbell register so that
controller sees the new request immediately.

Reviewed-by: Dolev Raviv <draviv@xxxxxxxxxxxxxx>
Signed-off-by: Gilad Broner <gbroner@xxxxxxxxxxxxxx>
Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
Signed-off-by: Yaniv Gardi <ygardi@xxxxxxxxxxxxxx>

---
 drivers/scsi/ufs/ufshcd.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index dfc4ac1..ec90504 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1628,6 +1628,8 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba,
 
 	hba->dev_cmd.complete = &wait;
 
+	/* Make sure descriptors are ready before ringing the doorbell */
+	wmb();
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	ufshcd_send_command(hba, tag);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
-- 
1.8.5.2

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