[U-Boot] [PATCH V3 2/2] mmc: sd: optimize erase

[Peng Fan]

To SD, there is no erase group, then the value erase_grp_size
will be default 1. When erasing SD blocks, the blocks will be
erased one by one, which is time consuming.

We use AU_SIZE as a group to speed up the erasing.

Erasing 4MB with a SD2.0 Card with AU_SIZE 4MB.
`time mmc erase 0x100000 0x2000`
time: 44.856 seconds (before optimization)
time: 0.335 seconds  (after optimization)

Signed-off-by: Peng Fan <peng.fan at nxp.com>
Cc: Jaehoon Chung <jh80.chung at samsung.com>
Cc: Simon Glass <sjg at chromium.org>
Cc: Bin Meng <bmeng.cn at gmail.com>
Cc: Stefan Wahren <stefan.wahren at i2se.com>
Cc: Clemens Gruber <clemens.gruber at pqgruber.com>
Cc: Kever Yang <kever.yang at rock-chips.com>
Cc: Eric Nelson <eric at nelint.com>
Cc: Stephen Warren <swarren at nvidia.com>
---

V3:
 No change.

V2:
 Add test results.

 drivers/mmc/mmc_write.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/mmc_write.c b/drivers/mmc/mmc_write.c
index 0f8b5c7..2289640 100644
--- a/drivers/mmc/mmc_write.c
+++ b/drivers/mmc/mmc_write.c
@@ -100,8 +100,13 @@ unsigned long mmc_berase(struct blk_desc *block_dev, lbaint_t start,
 		       & ~(mmc->erase_grp_size - 1)) - 1);
 
 	while (blk < blkcnt) {
-		blk_r = ((blkcnt - blk) > mmc->erase_grp_size) ?
-			mmc->erase_grp_size : (blkcnt - blk);
+		if (IS_SD(mmc) && mmc->ssr.au) {
+			blk_r = ((blkcnt - blk) > mmc->ssr.au) ?
+				mmc->ssr.au : (blkcnt - blk);
+		} else {
+			blk_r = ((blkcnt - blk) > mmc->erase_grp_size) ?
+				mmc->erase_grp_size : (blkcnt - blk);
+		}
 		err = mmc_erase_t(mmc, start + blk, blk_r);
 		if (err)
 			break;
-- 
2.6.2