mmc: core: Add quirk for long data read time

Adds a quirk that sets the data read timeout to a fixed value instead
of relying on the information in the CSD. The timeout value chosen
is 300ms since that has proven enough for the problematic cards found,
but could be increased if other cards require this.

This patch also enables this quirk for certain Micron cards known to
have this problem.

Signed-off-by: Stefan Nilsson XK <[e-mail]>
Signed-off-by: Ulf Hansson <[e-mail]>
Acked-by: Linus Walleij <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Chris Ball <[e-mail]>

drivers/mmc/card/block.c

···
 		  MMC_QUIRK_BLK_NO_CMD23),
 	MMC_FIXUP("MMC32G", 0x11, CID_OEMID_ANY, add_quirk_mmc,
 		  MMC_QUIRK_BLK_NO_CMD23),
+
+	/*
+	 * Some Micron MMC cards needs longer data read timeout than
+	 * indicated in CSD.
+	 */
+	MMC_FIXUP(CID_NAME_ANY, 0x13, 0x200, add_quirk_mmc,
+		  MMC_QUIRK_LONG_READ_TIME),
+
 	END_FIXUP
 };
 

drivers/mmc/core/core.c

···
 			data->timeout_clks = 0;
 		}
 	}
+
+	/*
+	 * Some cards require longer data read timeout than indicated in CSD.
+	 * Address this by setting the read timeout to a "reasonably high"
+	 * value. For the cards tested, 300ms has proven enough. If necessary,
+	 * this value can be increased if other problematic cards require this.
+	 */
+	if (mmc_card_long_read_time(card) && data->flags & MMC_DATA_READ) {
+		data->timeout_ns = 300000000;
+		data->timeout_clks = 0;
+	}
+
 	/*
 	 * Some cards need very high timeouts if driven in SPI mode.
 	 * The worst observed timeout was 900ms after writing a

include/linux/mmc/card.h

···
 #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 */
+#define MMC_QUIRK_LONG_READ_TIME (1<<9)		/* Data read time > CSD says */
 						/* byte mode */
 	unsigned int    poweroff_notify_state;	/* eMMC4.5 notify feature */
 #define MMC_NO_POWER_NOTIFICATION	0
···
 static inline int mmc_card_broken_byte_mode_512(const struct mmc_card *c)
 {
 	return c->quirks & MMC_QUIRK_BROKEN_BYTE_MODE_512;
+}
+
+static inline int mmc_card_long_read_time(const struct mmc_card *c)
+{
+	return c->quirks & MMC_QUIRK_LONG_READ_TIME;
 }
 
 #define mmc_card_name(c)	((c)->cid.prod_name)