mmc: core: Fix inconsistent sd3_bus_mode at UHS-I SD voltage switch failure

If re-initialization results is a different signal voltage, because the
voltage switch failed previously, but not this time (or vice versa), then
sd3_bus_mode will be inconsistent with the card because the SD_SWITCH
command is done only upon first initialization.

Fix by always reading SD_SWITCH information during re-initialization, which
also means it does not need to be re-read later for the 1.8V fixup
workaround.

Note, brief testing showed SD_SWITCH took about 1.8ms to 2ms which added
about 1% to 1.5% to the re-initialization time, so it's not particularly
significant.

Reported-by: Seunghui Lee <[email protected]>
Signed-off-by: Adrian Hunter <[email protected]>
Reviewed-by: Seunghui Lee <[email protected]>
Tested-by: Seunghui Lee <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ulf Hansson <[email protected]>

Author: ahunter6

drivers/mmc/core/sd.c

@@ -949,15 +949,16 @@ int mmc_sd_setup_card(struct mmc_host *host, struct mmc_card *card,
 
 		/* Erase init depends on CSD and SSR */
 		mmc_init_erase(card);
-
-		/*
-		 * Fetch switch information from card.
-		 */
-		err = mmc_read_switch(card);
-		if (err)
-			return err;
 	}
 
+	/*
+	 * Fetch switch information from card. Note, sd3_bus_mode can change if
+	 * voltage switch outcome changes, so do this always.
+	 */
+	err = mmc_read_switch(card);
+	if (err)
+		return err;
+
 	/*
 	 * For SPI, enable CRC as appropriate.
 	 * This CRC enable is located AFTER the reading of the
@@ -1480,26 +1481,15 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
 	if (!v18_fixup_failed && !mmc_host_is_spi(host) && mmc_host_uhs(host) &&
 	    mmc_sd_card_using_v18(card) &&
 	    host->ios.signal_voltage != MMC_SIGNAL_VOLTAGE_180) {
-		/*
-		 * Re-read switch information in case it has changed since
-		 * oldcard was initialized.
-		 */
-		if (oldcard) {
-			err = mmc_read_switch(card);
-			if (err)
-				goto free_card;
-		}
-		if (mmc_sd_card_using_v18(card)) {
-			if (mmc_host_set_uhs_voltage(host) ||
-			    mmc_sd_init_uhs_card(card)) {
-				v18_fixup_failed = true;
-				mmc_power_cycle(host, ocr);
-				if (!oldcard)
-					mmc_remove_card(card);
-				goto retry;
-			}
-			goto cont;
+		if (mmc_host_set_uhs_voltage(host) ||
+		    mmc_sd_init_uhs_card(card)) {
+			v18_fixup_failed = true;
+			mmc_power_cycle(host, ocr);
+			if (!oldcard)
+				mmc_remove_card(card);
+			goto retry;
 		}
+		goto cont;
 	}
 
 	/* Initialization sequence for UHS-I cards */