mmc: core: Allow host controllers to require R1B for CMD6

[ Upstream commit 1292e3ef ]

It has turned out that some host controllers can't use R1B for CMD6 and
other commands that have R1B associated with them. Therefore invent a new
host cap, MMC_CAP_NEED_RSP_BUSY to let them specify this.

In __mmc_switch(), let's check the flag and use it to prevent R1B responses
from being converted into R1. Note that, this also means that the host are
on its own, when it comes to manage the busy timeout.
Suggested-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Cc: <stable@vger.kernel.org>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Tested-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Tested-by: Faiz Abbas <faiz_abbas@ti.com>
Tested-By: Peter Geis <pgwipeout@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/mmc/core/mmc_ops.c

@@ -536,10 +536,12 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
 	 * If the cmd timeout and the max_busy_timeout of the host are both
 	 * specified, let's validate them. A failure means we need to prevent
 	 * the host from doing hw busy detection, which is done by converting
-	 * to a R1 response instead of a R1B.
+	 * to a R1 response instead of a R1B. Note, some hosts requires R1B,
+	 * which also means they are on their own when it comes to deal with the
+	 * busy timeout.
 	 */
-	if (timeout_ms && host->max_busy_timeout &&
-		(timeout_ms > host->max_busy_timeout))
+	if (!(host->caps & MMC_CAP_NEED_RSP_BUSY) && timeout_ms &&
+	    host->max_busy_timeout && (timeout_ms > host->max_busy_timeout))
 		use_r1b_resp = false;
 
 	cmd.opcode = MMC_SWITCH;

include/linux/mmc/host.h

@@ -332,6 +332,7 @@ struct mmc_host {
 				 MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | \
 				 MMC_CAP_UHS_DDR50)
 /* (1 << 21) is free for reuse */
+#define MMC_CAP_NEED_RSP_BUSY	(1 << 22)	/* Commands with R1B can't use R1. */
 #define MMC_CAP_DRIVER_TYPE_A	(1 << 23)	/* Host supports Driver Type A */
 #define MMC_CAP_DRIVER_TYPE_C	(1 << 24)	/* Host supports Driver Type C */
 #define MMC_CAP_DRIVER_TYPE_D	(1 << 25)	/* Host supports Driver Type D */