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

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Message-Id: <20191027203306.631189236@linuxfoundation.org>
Date:   Sun, 27 Oct 2019 22:01:16 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Faiz Abbas <faiz_abbas@...com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: [PATCH 4.19 64/93] mmc: cqhci: Commit descriptors before setting the doorbell

From: Faiz Abbas <faiz_abbas@...com>

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@...com>
Acked-by: Adrian Hunter <adrian.hunter@...el.com>
Cc: stable@...r.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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",