mmc: sd: filter card CQ support based on an allow-list

We have found that many SD cards in the field, even of the same make and
model, have latent bugs in their CQ implementation. Some product lines
have fewer bugs with newer manufacture dates, but this is not a
guarantee that a particular card is at a particular firmware revision
level.

Many of these bugs lead to card hangs or data corruption. Add a quirk to
mark a card as having a tested, working CQ implementation and ignore the
capability if absent.

Signed-off-by: Jonathan Bell <[email protected]>

Author: P33M

drivers/mmc/core/card.h

@@ -292,4 +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_working_sd_cq(const struct mmc_card *c)
+{
+	return c->quirks & MMC_QUIRK_WORKING_SD_CQ;
+}
+
 #endif

drivers/mmc/core/sd.c

@@ -1506,6 +1506,10 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
 			goto free_card;
 	}
 
+	/* Disallow command queueing on unvetted cards */
+	if (!mmc_card_working_sd_cq(card))
+		card->ext_csd.cmdq_support = false;
+
 	/* Enable command queueing if supported */
 	if (card->ext_csd.cmdq_support && host->caps2 & MMC_CAP2_CQE) {
 		/*

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_WORKING_SD_CQ	(1<<30)		/* SD card has known-good CQ implementation */
 #define MMC_QUIRK_ERASE_BROKEN	(1<<31)		/* Skip erase */
 
 	bool			written_flag;	/* Indicates eMMC has been written since power on */