[PATCH v3 14/15] scsi: ufs: commit descriptors before setting the doorbell

From: Yaniv Gardi
Date: Wed Sep 02 2015 - 06:14:40 EST

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.

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 298511a..eaf98bb 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1627,6 +1627,8 @@ 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);

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