linux-kernel - [PATCH V2] mmc: cqhci: DMA Configuration prior to CQE

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Message-ID: <1545251584-2105-2-git-send-email-skomatineni@nvidia.com>
Date:   Wed, 19 Dec 2018 12:33:04 -0800
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     <adrian.hunter@...el.com>, <ulf.hansson@...aro.org>
CC:     <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-mmc@...r.kernel.org>,
        Sowjanya Komatineni <skomatineni@...dia.com>
Subject: [PATCH V2] mmc: cqhci: DMA Configuration prior to CQE

eMMC-5.1 JESD84-B51 Spec (Section 6.6.39.1), mentions "Prior to
enabling command queuing, the block size shall be set to 512 B.
Device may respond with an error to CMD46/CMD47 if block size
is not 512 B".

This patch fixes the sequence to follow exact as per the spec.

Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
---
Changes for v2:
   - Updated commit message with JDEC Spec typo and exact spec reference
     on the requirement.

 drivers/mmc/host/cqhci.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/cqhci.c b/drivers/mmc/host/cqhci.c
index 159270e947cf..f701342e7212 100644
--- a/drivers/mmc/host/cqhci.c
+++ b/drivers/mmc/host/cqhci.c
@@ -248,6 +248,9 @@ static void __cqhci_enable(struct cqhci_host *cq_host)
 		cqhci_writel(cq_host, cqcfg, CQHCI_CFG);
 	}
 
+	if (cq_host->ops->enable)
+		cq_host->ops->enable(mmc);
+
 	cqcfg &= ~(CQHCI_DCMD | CQHCI_TASK_DESC_SZ);
 
 	if (mmc->caps2 & MMC_CAP2_CQE_DCMD)
@@ -273,9 +276,6 @@ static void __cqhci_enable(struct cqhci_host *cq_host)
 
 	mmc->cqe_on = true;
 
-	if (cq_host->ops->enable)
-		cq_host->ops->enable(mmc);
-
 	/* Ensure all writes are done before interrupts are enabled */
 	wmb();
 
@@ -561,6 +561,7 @@ static int cqhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
 	int tag = cqhci_tag(mrq);
 	struct cqhci_host *cq_host = mmc->cqe_private;
 	unsigned long flags;
+	u32 cqcfg = 0;
 
 	if (!cq_host->enabled) {
 		pr_err("%s: cqhci: not enabled\n", mmc_hostname(mmc));
@@ -579,8 +580,19 @@ static int cqhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
 			pr_err("%s: cqhci: CQE failed to exit halt state\n",
 			       mmc_hostname(mmc));
 		}
+		/* Configuration must not be changed while enabled */
+		cqcfg = cqhci_readl(cq_host, CQHCI_CFG);
+		if (cqcfg & CQHCI_ENABLE) {
+			cqcfg &= ~CQHCI_ENABLE;
+			cqhci_writel(cq_host, cqcfg, CQHCI_CFG);
+		}
+
 		if (cq_host->ops->enable)
 			cq_host->ops->enable(mmc);
+
+		cqcfg |= CQHCI_ENABLE;
+		cqhci_writel(cq_host, cqcfg, CQHCI_CFG);
+
 	}
 
 	if (mrq->data) {
-- 
2.7.4