linux-kernel - [PATCH v3 1/3] mmc:sdhci: Add a quirk for AMD SDHC transfer mode register need to be cleared for cmd without data

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Date:	Wed, 5 Nov 2014 14:09:00 +0800
From:	Vincent Wan <vincent.wan@....com>
To:	Ulf Hansson <ulf.hansson@...aro.org>
CC:	<linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Arindam Nath <arindam.nath@....com>,
	Huang Rui <ray.huang@....com>,
	Wan Zongshun <mcuos.com@...il.com>,
	Vincent Wan <vincent.wan@....com>
Subject: [PATCH v3 1/3] mmc:sdhci: Add a quirk for AMD SDHC transfer mode register need to be cleared for cmd without data

SDHC controller in AMD chipsets require SDHC transfer mode
register to be cleared for commands without data. The issue was
uncovered during testing eMMC cards on KB/ML based platforms

Signed-off-by: Vincent Wan <vincent.wan@....com>
Signed-off-by: Wan Zongshun <mcuos.com@...il.com>
Signed-off-by: Arindam Nath <arindam.nath@....com>
Tested-by: Vikram B <vikram.b@....com>
Tested-by: Raghavendra Swamy <raghavendra.swamy@....com>
---
 drivers/mmc/host/sdhci.c  | 9 +++++++--
 include/linux/mmc/sdhci.h | 2 ++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index f895ab0..a743d52 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -915,10 +915,15 @@ static void sdhci_set_transfer_mode(struct sdhci_host *host,
 	struct mmc_data *data = cmd->data;
 
 	if (data == NULL) {
+		if (host->quirks2 &
+			SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD) {
+			sdhci_writew(host, 0x0, SDHCI_TRANSFER_MODE);
+		} else {
 		/* clear Auto CMD settings for no data CMDs */
-		mode = sdhci_readw(host, SDHCI_TRANSFER_MODE);
-		sdhci_writew(host, mode & ~(SDHCI_TRNS_AUTO_CMD12 |
+			mode = sdhci_readw(host, SDHCI_TRANSFER_MODE);
+			sdhci_writew(host, mode & ~(SDHCI_TRNS_AUTO_CMD12 |
 				SDHCI_TRNS_AUTO_CMD23), SDHCI_TRANSFER_MODE);
+		}
 		return;
 	}
 
diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
index 931ac5e..ae7f357 100644
--- a/include/linux/mmc/sdhci.h
+++ b/include/linux/mmc/sdhci.h
@@ -102,6 +102,8 @@ struct sdhci_host {
 #define SDHCI_QUIRK2_STOP_WITH_TC			(1<<8)
 /* Controller does not support 64-bit DMA */
 #define SDHCI_QUIRK2_BROKEN_64_BIT_DMA			(1<<9)
+/* need clear transfer mode register before send cmd */
+#define SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD	(1<<10)
 
 	int irq;		/* Device IRQ */
 	void __iomem *ioaddr;	/* Mapped address */
-- 
1.8.1.2

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