scsi: ufs: commit descriptors before setting the doorbell

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@codeaurora.org>
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 1893a14..2fc678d 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1625,6 +1625,8 @@ 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);