MMC: Always use a sector size of 512 bytes

Both MMC and SD specifications specify (although a bit unclearly in the MMC
case) that a sector size of 512 bytes must always be supported by the card.

Cards can report larger "native" size than this, and cards >= 2 GB even
must do so. Most other readers use 512 bytes even for these cards. We should
do the same to be compatible.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Cc: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/mmc/mmc_block.c b/drivers/mmc/mmc_block.c
index 587458b370b9a9d71c817d0375d140847f01c505..96049e24ed31fa75570c536c03bfaaba9afc97fd 100644 (file)
--- a/drivers/mmc/mmc_block.c
+++ b/drivers/mmc/mmc_block.c
@@ -325,52 +325,11 @@ static struct mmc_blk_data *mmc_blk_alloc(struct mmc_card *card)
        md->read_only = mmc_blk_readonly(card);
 
        /*
-        * Figure out a workable block size.  MMC cards have:
-        *  - two block sizes, one for read and one for write.
-        *  - may support partial reads and/or writes
-        *    (allows block sizes smaller than specified)
+        * Both SD and MMC specifications state (although a bit
+        * unclearly in the MMC case) that a block size of 512
+        * bytes must always be supported by the card.
         */
-       md->block_bits = card->csd.read_blkbits;
-       if (card->csd.write_blkbits != card->csd.read_blkbits) {
-               if (card->csd.write_blkbits < card->csd.read_blkbits &&
-                   card->csd.read_partial) {
-                       /*
-                        * write block size is smaller than read block
-                        * size, but we support partial reads, so choose
-                        * the smaller write block size.
-                        */
-                       md->block_bits = card->csd.write_blkbits;
-               } else if (card->csd.write_blkbits > card->csd.read_blkbits &&
-                          card->csd.write_partial) {
-                       /*
-                        * read block size is smaller than write block
-                        * size, but we support partial writes.  Use read
-                        * block size.
-                        */
-               } else {
-                       /*
-                        * We don't support this configuration for writes.
-                        */
-                       printk(KERN_ERR "%s: unable to select block size for "
-                               "writing (rb%u wb%u rp%u wp%u)\n",
-                               mmc_card_id(card),
-                               1 << card->csd.read_blkbits,
-                               1 << card->csd.write_blkbits,
-                               card->csd.read_partial,
-                               card->csd.write_partial);
-                       md->read_only = 1;
-               }
-       }
-
-       /*
-        * Refuse to allow block sizes smaller than 512 bytes.
-        */
-       if (md->block_bits < 9) {
-               printk(KERN_ERR "%s: unable to support block size %u\n",
-                       mmc_card_id(card), 1 << md->block_bits);
-               ret = -EINVAL;
-               goto err_kfree;
-       }
+       md->block_bits = 9;
 
        md->disk = alloc_disk(1 << MMC_SHIFT);
        if (md->disk == NULL) {