[RFC 3/3] MMC: Block CMD23 support for UHS104/SDXC cards.

[Andrei Warkentin]

SD cards operating at UHS104 or better support SET_BLOCK_COUNT.

Signed-off-by: Andrei Warkentin <andr...@motorola.com>
---
 drivers/mmc/card/block.c |    9 ++++++---
 drivers/mmc/core/sd.c    |    1 +
 include/linux/mmc/card.h |    1 +
 include/linux/mmc/sd.h   |    1 +
 4 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 282e6ef..6573e36 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -846,9 +846,12 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct 
mmc_card *card,
        blk_queue_logical_block_size(md->queue.queue, 512);
        set_capacity(md->disk, size);
 
-       if (mmc_host_cmd23(card->host) &&
-           mmc_card_mmc(card))
-               md->flags |= MMC_BLK_CMD23;
+       if (mmc_host_cmd23(card->host)) {
+               if (mmc_card_mmc(card) ||
+                   (mmc_card_sd(card) &&
+                    card->scr.cmds & SCR_CMDS_CMD23))
+                       md->flags |= MMC_BLK_CMD23;
+       }
 
        if (mmc_card_mmc(card) &&
            md->flags & MMC_BLK_CMD23 &&
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 6dac89f..16a1f10 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -195,6 +195,7 @@ static int mmc_decode_scr(struct mmc_card *card)
        else
                card->erased_byte = 0x0;
 
+       scr->cmds = UNSTUFF_BITS(resp, 32, 2);
        return 0;
 }
 
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 72a9868..337a851 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -70,6 +70,7 @@ struct sd_scr {
        unsigned char           bus_widths;
 #define SD_SCR_BUS_WIDTH_1     (1<<0)
 #define SD_SCR_BUS_WIDTH_4     (1<<2)
+       unsigned char           cmds;
 };
 
 struct sd_ssr {
diff --git a/include/linux/mmc/sd.h b/include/linux/mmc/sd.h
index 3fd85e0..81ba37b 100644
--- a/include/linux/mmc/sd.h
+++ b/include/linux/mmc/sd.h
@@ -60,6 +60,7 @@
 #define SCR_SPEC_VER_0         0       /* Implements system specification 1.0 
- 1.01 */
 #define SCR_SPEC_VER_1         1       /* Implements system specification 1.10 
*/
 #define SCR_SPEC_VER_2         2       /* Implements system specification 2.00 
*/
+#define SCR_CMDS_CMD23         (1 << 1) /* Supports CMD23 */
 
 /*
  * SD bus widths
-- 
1.7.0.4

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