mmc: fixes for eMMC v4.5 discard operation

eMMC v4.5 discard operation is significantly different from the
existing trim operation because it is not guaranteed to work with
the new sanitize operation.  Consequently mmc_can_trim() is
separated from mmc_can_discard().

Also the new discard operation does not result in the sectors being
set to all-zeros, so discard_zeroes_data must not be set.

In addition, the new discard has the same timeout as trim, but from
v4.5 trim is defined to use the hc timeout.  The timeout calculation
is adjusted accordingly.

Fixes apply to linux 3.2 on.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: <stable@vger.kernel.org>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/card/queue.c

@@ -139,7 +139,7 @@ static void mmc_queue_setup_discard(struct request_queue *q,
 
 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
 	q->limits.max_discard_sectors = max_discard;
-	if (card->erased_byte == 0)
+	if (card->erased_byte == 0 && !mmc_can_discard(card))
 		q->limits.discard_zeroes_data = 1;
 	q->limits.discard_granularity = card->pref_erase << 9;
 	/* granularity must not be greater than max. discard */

drivers/mmc/core/core.c

@@ -1409,7 +1409,10 @@ static unsigned int mmc_mmc_erase_timeout(struct mmc_card *card,
 {
 	unsigned int erase_timeout;
 
-	if (card->ext_csd.erase_group_def & 1) {
+	if (arg == MMC_DISCARD_ARG ||
+	    (arg == MMC_TRIM_ARG && card->ext_csd.rev >= 6)) {
+		erase_timeout = card->ext_csd.trim_timeout;
+	} else if (card->ext_csd.erase_group_def & 1) {
 		/* High Capacity Erase Group Size uses HC timeouts */
 		if (arg == MMC_TRIM_ARG)
 			erase_timeout = card->ext_csd.trim_timeout;
@@ -1681,8 +1684,6 @@ int mmc_can_trim(struct mmc_card *card)
 {
 	if (card->ext_csd.sec_feature_support & EXT_CSD_SEC_GB_CL_EN)
 		return 1;
-	if (mmc_can_discard(card))
-		return 1;
 	return 0;
 }
 EXPORT_SYMBOL(mmc_can_trim);