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@amd.com>
Signed-off-by: Wan Zongshun <mcuos.com@gmail.com>
Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Tested-by: Vikram B <vikram.b@amd.com>
Tested-by: Raghavendra Swamy <raghavendra.swamy@amd.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

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 |
 				SDHCI_TRNS_AUTO_CMD23), SDHCI_TRANSFER_MODE);
+		}
 		return;
 	}
 

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 */