mmc: Add quirk to disable DDR50 tuning

Adds the MMC_QUIRK_NO_UHS_DDR50_TUNING quirk and updates
mmc_execute_tuning() to return 0 if that quirk is set. This fixes an
issue on certain Swissbit SD cards that do not support DDR50 tuning
where tuning requests caused I/O errors to be thrown.

Signed-off-by: Erick Shepherd <[email protected]>

Author: erickshepherdNI

drivers/mmc/core/card.h

@@ -86,6 +86,7 @@ struct mmc_fixup {
 #define CID_MANFID_MICRON       0x13
 #define CID_MANFID_SAMSUNG      0x15
 #define CID_MANFID_APACER       0x27
+#define CID_MANFID_SWISSBIT     0x5D
 #define CID_MANFID_KINGSTON     0x70
 #define CID_MANFID_HYNIX	0x90
 #define CID_MANFID_KINGSTON_SD	0x9F
@@ -291,4 +292,9 @@ static inline int mmc_card_broken_sd_poweroff_notify(const struct mmc_card *c)
 	return c->quirks & MMC_QUIRK_BROKEN_SD_POWEROFF_NOTIFY;
 }
 
+static inline int mmc_card_no_uhs_ddr50_tuning(const struct mmc_card *c)
+{
+	return c->quirks & MMC_QUIRK_NO_UHS_DDR50_TUNING;
+}
+
 #endif

drivers/mmc/core/quirks.h

@@ -34,6 +34,16 @@ static const struct mmc_fixup __maybe_unused mmc_sd_fixups[] = {
 		   MMC_QUIRK_BROKEN_SD_CACHE | MMC_QUIRK_BROKEN_SD_POWEROFF_NOTIFY,
 		   EXT_CSD_REV_ANY),
 
+	/*
+	 * Swissbit series S46-u cards throw I/O errors during tuning requests
+	 * after the initial tuning request expectedly times out. This has
+	 * only been observed on cards manufactured on 01/2019 that are using
+	 * Bay Trail host controllers.
+	 */
+	_FIXUP_EXT("0016G", CID_MANFID_SWISSBIT, 0x5342, 2019, 1,
+		   0, -1ull, SDIO_ANY_ID, SDIO_ANY_ID, add_quirk_sd,
+		   MMC_QUIRK_NO_UHS_DDR50_TUNING, EXT_CSD_REV_ANY),
+
 	END_FIXUP
 };
 

drivers/mmc/core/sd.c

@@ -618,6 +618,29 @@ static int sd_set_current_limit(struct mmc_card *card, u8 *status)
 	return 0;
 }
 
+/*
+ * Determine if the card should tune or not.
+ */
+static bool mmc_sd_use_tuning(struct mmc_card *card)
+{
+	/*
+	 * SPI mode doesn't define CMD19 and tuning is only valid for SDR50 and
+	 * SDR104 mode SD-cards. Note that tuning is mandatory for SDR104.
+	 */
+	if (mmc_host_is_spi(card->host))
+		return false;
+
+	switch (card->host->ios.timing) {
+	case MMC_TIMING_UHS_SDR50:
+	case MMC_TIMING_UHS_SDR104:
+		return true;
+	case MMC_TIMING_UHS_DDR50:
+		return !mmc_card_no_uhs_ddr50_tuning(card);
+	}
+
+	return false;
+}
+
 /*
  * UHS-I specific initialization procedure
  */
@@ -661,14 +684,7 @@ static int mmc_sd_init_uhs_card(struct mmc_card *card)
 	if (err)
 		goto out;
 
-	/*
-	 * SPI mode doesn't define CMD19 and tuning is only valid for SDR50 and
-	 * SDR104 mode SD-cards. Note that tuning is mandatory for SDR104.
-	 */
-	if (!mmc_host_is_spi(card->host) &&
-		(card->host->ios.timing == MMC_TIMING_UHS_SDR50 ||
-		 card->host->ios.timing == MMC_TIMING_UHS_DDR50 ||
-		 card->host->ios.timing == MMC_TIMING_UHS_SDR104)) {
+	if (mmc_sd_use_tuning(card)) {
 		err = mmc_execute_tuning(card);
 
 		/*

include/linux/mmc/card.h

@@ -297,6 +297,7 @@ struct mmc_card {
 #define MMC_QUIRK_BROKEN_SD_CACHE	(1<<15)	/* Disable broken SD cache support */
 #define MMC_QUIRK_BROKEN_CACHE_FLUSH	(1<<16)	/* Don't flush cache until the write has occurred */
 #define MMC_QUIRK_BROKEN_SD_POWEROFF_NOTIFY	(1<<17) /* Disable broken SD poweroff notify support */
+#define MMC_QUIRK_NO_UHS_DDR50_TUNING	(1<<18) /* Disable DDR50 tuning */
 
 	bool			written_flag;	/* Indicates eMMC has been written since power on */
 	bool			reenable_cmdq;	/* Re-enable Command Queue */