mmc: core: Fix partition switch time for eMMC

Avoid the following warning by always defining partition switch time:

 [    3.209874] mmc1: unspecified timeout for CMD6 - use generic
 [    3.222780] ------------[ cut here ]------------
 [    3.233363] WARNING: CPU: 1 PID: 111 at drivers/mmc/core/mmc_ops.c:575 __mmc_switch+0x200/0x204
Reported-by: Paul Fertser <fercerpav@gmail.com>
Fixes: 1c447116 ("mmc: mmc: Fix partition switch timeout for some eMMCs")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/168bbfd6-0c5b-5ace-ab41-402e7937c46e@intel.com
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/mmc.c

@@ -423,10 +423,6 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
 
 		/* EXT_CSD value is in units of 10ms, but we store in ms */
 		card->ext_csd.part_time = 10 * ext_csd[EXT_CSD_PART_SWITCH_TIME];
-		/* Some eMMC set the value too low so set a minimum */
-		if (card->ext_csd.part_time &&
-		    card->ext_csd.part_time < MMC_MIN_PART_SWITCH_TIME)
-			card->ext_csd.part_time = MMC_MIN_PART_SWITCH_TIME;
 
 		/* Sleep / awake timeout in 100ns units */
 		if (sa_shift > 0 && sa_shift <= 0x17)
@@ -616,6 +612,17 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
 		card->ext_csd.data_sector_size = 512;
 	}
 
+	/*
+	 * GENERIC_CMD6_TIME is to be used "unless a specific timeout is defined
+	 * when accessing a specific field", so use it here if there is no
+	 * PARTITION_SWITCH_TIME.
+	 */
+	if (!card->ext_csd.part_time)
+		card->ext_csd.part_time = card->ext_csd.generic_cmd6_time;
+	/* Some eMMC set the value too low so set a minimum */
+	if (card->ext_csd.part_time < MMC_MIN_PART_SWITCH_TIME)
+		card->ext_csd.part_time = MMC_MIN_PART_SWITCH_TIME;
+
 	/* eMMC v5 or later */
 	if (card->ext_csd.rev >= 7) {
 		memcpy(card->ext_csd.fwrev, &ext_csd[EXT_CSD_FIRMWARE_VERSION],