mmc: sdio: add a quirk for broken SDIO_CCCR_INTx polling

Polling SDIO_CCCR_INTx could create a fake interrupt with Marvell
SD8797 card. Add a quirk to handle this case. The fixup here is
to issue a dummy CMD52 read to function 0 register 0xff, and this
dummy read must be right after SDIO_CCCR_INTx is read.

Patch has been verified on a dw_mmc controller (Samsung Chromebook)
with MMC_CAP_SDIO_IRQ disabled.
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <chris@printf.net>

drivers/mmc/core/quirks.c

@@ -13,6 +13,7 @@
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/mmc/card.h>
+#include <linux/mmc/sdio_ids.h>
 
 #ifndef SDIO_VENDOR_ID_TI
 #define SDIO_VENDOR_ID_TI		0x0097
@@ -30,6 +31,10 @@
 #define SDIO_DEVICE_ID_STE_CW1200	0x2280
 #endif
 
+#ifndef SDIO_DEVICE_ID_MARVELL_8797_F0
+#define SDIO_DEVICE_ID_MARVELL_8797_F0	0x9128
+#endif
+
 /*
  * This hook just adds a quirk for all sdio devices
  */
@@ -58,6 +63,9 @@ static const struct mmc_fixup mmc_fixup_methods[] = {
 	SDIO_FIXUP(SDIO_VENDOR_ID_STE, SDIO_DEVICE_ID_STE_CW1200,
 		   add_quirk, MMC_QUIRK_BROKEN_BYTE_MODE_512),
 
+	SDIO_FIXUP(SDIO_VENDOR_ID_MARVELL, SDIO_DEVICE_ID_MARVELL_8797_F0,
+		   add_quirk, MMC_QUIRK_BROKEN_IRQ_POLLING),
+
 	END_FIXUP
 };
 

drivers/mmc/core/sdio_irq.c

@@ -53,6 +53,17 @@ static int process_sdio_pending_irqs(struct mmc_host *host)
 		return ret;
 	}
 
+	if (pending && mmc_card_broken_irq_polling(card) &&
+	    !(host->caps & MMC_CAP_SDIO_IRQ)) {
+		unsigned char dummy;
+
+		/* A fake interrupt could be created when we poll SDIO_CCCR_INTx
+		 * register with a Marvell SD8797 card. A dummy CMD52 read to
+		 * function 0 register 0xff can avoid this.
+		 */
+		mmc_io_rw_direct(card, 0, 0, 0xff, 0, &dummy);
+	}
+
 	count = 0;
 	for (i = 1; i <= 7; i++) {
 		if (pending & (1 << i)) {

include/linux/mmc/card.h

@@ -271,9 +271,10 @@ struct mmc_card {
 #define MMC_QUIRK_INAND_CMD38	(1<<6)		/* iNAND devices have broken CMD38 */
 #define MMC_QUIRK_BLK_NO_CMD23	(1<<7)		/* Avoid CMD23 for regular multiblock */
 #define MMC_QUIRK_BROKEN_BYTE_MODE_512 (1<<8)	/* Avoid sending 512 bytes in */
+						/* byte mode */
 #define MMC_QUIRK_LONG_READ_TIME (1<<9)		/* Data read time > CSD says */
 #define MMC_QUIRK_SEC_ERASE_TRIM_BROKEN (1<<10)	/* Skip secure for erase/trim */
-						/* byte mode */
+#define MMC_QUIRK_BROKEN_IRQ_POLLING	(1<<11)	/* Polling SDIO_CCCR_INTx could create a fake interrupt */
 
 	unsigned int		erase_size;	/* erase size in sectors */
  	unsigned int		erase_shift;	/* if erase unit is power 2 */
@@ -505,6 +506,11 @@ static inline int mmc_card_long_read_time(const struct mmc_card *c)
 	return c->quirks & MMC_QUIRK_LONG_READ_TIME;
 }
 
+static inline int mmc_card_broken_irq_polling(const struct mmc_card *c)
+{
+	return c->quirks & MMC_QUIRK_BROKEN_IRQ_POLLING;
+}
+
 #define mmc_card_name(c)	((c)->cid.prod_name)
 #define mmc_card_id(c)		(dev_name(&(c)->dev))