[PATCH 3.16 070/306] mmc: block: don't use CMD23 with very old MMC cards

[Ben Hutchings]

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel GlÃckner <dg@xxxxxxxxx>

commit 0ed50abb2d8fc81570b53af25621dad560cd49b3 upstream.

CMD23 aka SET_BLOCK_COUNT was introduced with MMC v3.1.
Older versions of the specification allowed to terminate
multi-block transfers only with CMD12.

The patch fixes the following problem:

  mmc0: new MMC card at address 0001
  mmcblk0: mmc0:0001 SDMB-16 15.3 MiB
  mmcblk0: timed out sending SET_BLOCK_COUNT command, card status 0x400900
  ...
  blk_update_request: I/O error, dev mmcblk0, sector 0
  Buffer I/O error on dev mmcblk0, logical block 0, async page read
   mmcblk0: unable to read partition table

Signed-off-by: Daniel GlÃckner <dg@xxxxxxxxx>
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/mmc/card/block.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -2170,7 +2170,8 @@ static struct mmc_blk_data *mmc_blk_allo
 	set_capacity(md->disk, size);
 
 	if (mmc_host_cmd23(card->host)) {
-		if (mmc_card_mmc(card) ||
+		if ((mmc_card_mmc(card) &&
+		     card->csd.mmca_vsn >= CSD_SPEC_VER_3) ||
 		    (mmc_card_sd(card) &&
 		     card->scr.cmds & SD_SCR_CMD23_SUPPORT))
 			md->flags |= MMC_BLK_CMD23;