mmc: queue: bring discard_granularity/alignment into line with SCSI

SCSI defines discard alignment as the offset to the first
optimal discard.  In the case of SD/MMC, that is always zero
which is the default.

SCSI defines discard granularity as a hint of a optimal
discard size.  That is much better expressed by the MMC
"preferred erase size" (pref_erase) field.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 1 insertions, 6 deletions

diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index 3e2db1cf1cbb..6413afa318d2 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -135,12 +135,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
                 mq->queue->limits.max_discard_sectors = UINT_MAX;
                 if (card->erased_byte == 0)
                         mq->queue->limits.discard_zeroes_data = 1;
-                if (!mmc_can_trim(card) && is_power_of_2(card->erase_size)) {
-                        mq->queue->limits.discard_granularity =
-                                                        card->erase_size << 9;
-                        mq->queue->limits.discard_alignment =
-                                                        card->erase_size << 9;
-                }
+                mq->queue->limits.discard_granularity = card->pref_erase << 9;
                 if (mmc_can_secure_erase_trim(card))
                         queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD,
                                                 mq->queue);