[PATCH] mmc: Add a quirk for AMD SDHC transfer mode register need to be cleared for cmd without data

[Vincent Wan <vincent.wan@amd.com>]

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: Arindam Nath <arindam.nath@amd.com>
Tested-by: Vikram B <vikram.b@amd.com>
Tested-by: Raghavendra Swamy <raghavendra.swamy@amd.com>

---
  drivers/mmc/host/sdhci-pci.c | 27 +++++++++++++++++++++++++++
  drivers/mmc/host/sdhci.c     | 11 ++++++++---
  include/linux/mmc/sdhci.h    |  2 ++
  3 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/sdhci-pci.c b/drivers/mmc/host/sdhci-pci.c
index 6119297..8f5c998 100644
--- a/drivers/mmc/host/sdhci-pci.c
+++ b/drivers/mmc/host/sdhci-pci.c
@@ -645,6 +645,23 @@ static const struct sdhci_pci_fixes sdhci_rtsx = {
  	.probe_slot	= rtsx_probe_slot,
  };

+static int amd_probe(struct sdhci_pci_chip *chip)
+{
+	struct pci_dev	*smbus_dev;
+
+	smbus_dev = pci_get_device(PCI_VENDOR_ID_AMD,
+			PCI_DEVICE_ID_AMD_HUDSON2_SMBUS, NULL);
+
+	if (smbus_dev && (smbus_dev->revision < 0x51))
+		chip->quirks2 |= SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD;
+
+	return 0;
+}
+
+static const struct sdhci_pci_fixes sdhci_amd = {
+	.probe		= amd_probe,
+};
+
  static const struct pci_device_id pci_ids[] = {
  	{
  		.vendor		= PCI_VENDOR_ID_RICOH,
@@ -1045,6 +1062,16 @@ static const struct pci_device_id pci_ids[] = {
  		.driver_data	= (kernel_ulong_t)&sdhci_o2,
  	},

+	{
+		.vendor		= PCI_VENDOR_ID_AMD,
+		.device		= PCI_ANY_ID,
+		.class		= PCI_CLASS_SYSTEM_SDHCI << 8,
+		.class_mask	= 0xFFFF00,
+		.subvendor	= PCI_ANY_ID,
+		.subdevice	= PCI_ANY_ID,
+		.driver_data	= (kernel_ulong_t)&sdhci_amd,
+	},
+
  	{	/* Generic SD host controller */
  		PCI_DEVICE_CLASS((PCI_CLASS_SYSTEM_SDHCI << 8), 0xFFFF00)
  	},
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index ada1a3e..8085f26 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -889,10 +889,15 @@ static void sdhci_set_transfer_mode(struct 
sdhci_host *host,
  	struct mmc_data *data = cmd->data;

  	if (data == NULL) {
-		/* clear Auto CMD settings for no data CMDs */
-		mode = sdhci_readw(host, SDHCI_TRANSFER_MODE);
-		sdhci_writew(host, mode & ~(SDHCI_TRNS_AUTO_CMD12 |
+		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;
  	}

diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
index dba793e..0a287aa 100644
--- a/include/linux/mmc/sdhci.h
+++ b/include/linux/mmc/sdhci.h
@@ -100,6 +100,8 @@ struct sdhci_host {
  #define SDHCI_QUIRK2_BROKEN_DDR50			(1<<7)
  /* Stop command (CMD12) can set Transfer Complete when not using 
MMC_RSP_BUSY */
  #define SDHCI_QUIRK2_STOP_WITH_TC			(1<<8)
+/* need clear transfer mode register before send cmd */
+#define SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD	(1<<9)

  	int irq;		/* Device IRQ */
  	void __iomem *ioaddr;	/* Mapped address */
-- 
1.8.1.2