[MMC] Improve MMC card block size selection

Select a block size for IO based on the read and write block size
combinations, and whether the card supports partial block reads
and/or partial block writes.

If we are able to satisfy block reads but not block writes, mark
the device read only.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index eb41391e06e9..6696f71363b9 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -550,6 +550,11 @@ static void mmc_decode_csd(struct mmc_card *card)
                 csd->capacity     = (1 + m) << (e + 2);
 
                 csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
+                csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
+                csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
+                csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
+                csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
+                csd->write_partial = UNSTUFF_BITS(resp, 21, 1);
         } else {
                 /*
                  * We only understand CSD structure v1.1 and v1.2.
@@ -579,6 +584,11 @@ static void mmc_decode_csd(struct mmc_card *card)
                 csd->capacity     = (1 + m) << (e + 2);
 
                 csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
+                csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
+                csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
+                csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
+                csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
+                csd->write_partial = UNSTUFF_BITS(resp, 21, 1);
         }
 }