mmc: core: Improve fallback to speed modes if eMMC HS200 fails

In the error path of mmc_select_hs200() we are trying our best to restore the card/host into a valid state. This makes sense, especially if we encounter a simple switch error (-EBADMSG). However, rather than then continue with using the legacy speed mode, let's try the other better speed modes first. Additionally, let's update the card->mmc_avail_type to avoid us from trying a broken HS200 mode again. In an Amlogic S905W based TV box where the switch to HS200 mode fails for the eMMC, this allows us to use the eMMC in DDR mode in favor of the legacy mode, which greatly improves the performance. Suggested-by: Heiner Kallweit <[email protected]> Signed-off-by: Ulf Hansson <[email protected]> Tested-by: Heiner Kallweit <[email protected]> Link: https://lore.kernel.org/r/[email protected]
LoveHeat · Mar 15, 2022 · 3b6c472 · 3b6c472
1 parent e23b2f5
commit 3b6c472
Showing 1 changed file with 13 additions and 3 deletions.
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
@@ -1523,13 +1523,23 @@ static int mmc_select_timing(struct mmc_card *card)
 	if (!mmc_can_ext_csd(card))
 		goto bus_speed;
 
-	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES)
+	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES) {
 		err = mmc_select_hs400es(card);
-	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
+		goto out;
+	}
+
+	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200) {
 		err = mmc_select_hs200(card);
-	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
+		if (err == -EBADMSG)
+			card->mmc_avail_type &= ~EXT_CSD_CARD_TYPE_HS200;
+		else
+			goto out;
+	}
+
+	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
 		err = mmc_select_hs(card);
 
+out:
 	if (err && err != -EBADMSG)
 		return err;