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

drivers/mmc/core/core.c

@@ -931,6 +931,10 @@ int mmc_execute_tuning(struct mmc_card *card)
 	if (!host->ops->execute_tuning)
 		return 0;
 
+	if ((card->quirks & MMC_QUIRK_NO_UHS_DDR50_TUNING) &&
+		host->ios.timing == MMC_TIMING_UHS_DDR50)
+			return 0;
+
 	if (host->cqe_on)
 		host->cqe_ops->cqe_off(host);
 

drivers/mmc/core/quirks.h

@@ -34,6 +34,14 @@ 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),
 
+	/*
+	 * Certain DDR50 Swissbit SD cards built to the 3.0 SD spec, which
+	 * do not support tuning, throw I/O errors during tuning requests.
+	 * This has only been observed on Bay Trail host controllers.
+	 */
+	MMC_FIXUP("0016G", CID_MANFID_SWISSBIT, 0x5342, add_quirk,
+		   MMC_QUIRK_NO_UHS_DDR50_TUNING),
+
 	END_FIXUP
 };
 

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 */