[PATCH 4.19 64/93] mmc: cqhci: Commit descriptors before setting the doorbell

[Greg Kroah-Hartman]

From: Faiz Abbas <faiz_abbas@xxxxxx>

commit c07d0073b9ec80a139d07ebf78e9c30d2a28279e upstream.

Add a write memory barrier to make sure that descriptors are actually
written to memory, before ringing the doorbell.

Signed-off-by: Faiz Abbas <faiz_abbas@xxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/mmc/host/cqhci.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/mmc/host/cqhci.c
+++ b/drivers/mmc/host/cqhci.c
@@ -617,7 +617,8 @@ static int cqhci_request(struct mmc_host
 	cq_host->slot[tag].flags = 0;
 
 	cq_host->qcnt += 1;
-
+	/* Make sure descriptors are ready before ringing the doorbell */
+	wmb();
 	cqhci_writel(cq_host, 1 << tag, CQHCI_TDBR);
 	if (!(cqhci_readl(cq_host, CQHCI_TDBR) & (1 << tag)))
 		pr_debug("%s: cqhci: doorbell not set for tag %d\n",