[PATCH 1/3] mmc: sdhci: fix SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD handling

["ernest.zhang" <ernest.zhang@bayhubtech.com>]

SD controller with SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD quirk
will clear SD host transfer mode register for non-data commands. But in
eMMC HS200 hardware tuning case, the hardware tuning process need to
transfer mode register has properly value. So don't clear transfer
mode register when opcode equals to MMC_SEND_TUNING_BLOCK_HS200.

Signed-off-by: ernest.zhang <ernest.zhang@bayhubtech.com>
---
 drivers/mmc/host/sdhci.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 0d5fcca18c9e..d5b19fc9ea56 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -918,7 +918,9 @@ static void sdhci_set_transfer_mode(struct sdhci_host *host,
 	if (data == NULL) {
 		if (host->quirks2 &
 			SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD) {
-			sdhci_writew(host, 0x0, SDHCI_TRANSFER_MODE);
+			/* cannot clear transfer mode register when tuning */
+			if (cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200)
+				sdhci_writew(host, 0x0, SDHCI_TRANSFER_MODE);
 		} else {
 		/* clear Auto CMD settings for no data CMDs */
 			mode = sdhci_readw(host, SDHCI_TRANSFER_MODE);
-- 
2.14.1