mmc: block: Pause re-tuning while switched to the RPMB partition

Re-tuning is not possible when switched to the RPMB
partition.  However re-tuning should not be needed
if re-tuning is done immediately before switching,
a small set of operations is done, and then we
immediately switch back to the main partition.

A previous patch ensured that we immediately switch
back to the main partition.

This patch uses the new facility to "pause" re-tuning
before switching to the RPMB partition, and to "unpause"
it after switching from the RPMB partition.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/card/block.c

@@ -756,16 +756,25 @@ static inline int mmc_blk_part_switch(struct mmc_card *card,
 	if (mmc_card_mmc(card)) {
 		u8 part_config = card->ext_csd.part_config;
 
+		if (md->part_type == EXT_CSD_PART_CONFIG_ACC_RPMB)
+			mmc_retune_pause(card->host);
+
 		part_config &= ~EXT_CSD_PART_CONFIG_ACC_MASK;
 		part_config |= md->part_type;
 
 		ret = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
 				 EXT_CSD_PART_CONFIG, part_config,
 				 card->ext_csd.part_time);
-		if (ret)
+		if (ret) {
+			if (md->part_type == EXT_CSD_PART_CONFIG_ACC_RPMB)
+				mmc_retune_unpause(card->host);
 			return ret;
+		}
 
 		card->ext_csd.part_config = part_config;
+
+		if (main_md->part_curr == EXT_CSD_PART_CONFIG_ACC_RPMB)
+			mmc_retune_unpause(card->host);
 	}
 
 	main_md->part_curr = md->part_type;