PATCH: Force MMC/SD to 512 byte block sizes.

Angry customers and investigation into USB attached MMC/SD
readers have lead us to believe that the SD device block size should
be fixed at 512 bytes regardless of the block size reported by the card.
This comes into play with >2G cards.  After applying this fix, filesystems
written with a USB card reader can be read by the MMC subsystem and 
vice-versa.

Signed-off-by: Jordan Crouse <jordan.crouse@amd.com>
---

 drivers/mmc/mmc_block.c |   16 +++++++++++++---
 1 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/mmc_block.c b/drivers/mmc/mmc_block.c
index d91fcf7..96fa121 100644
--- a/drivers/mmc/mmc_block.c
+++ b/drivers/mmc/mmc_block.c
@@ -303,6 +303,7 @@ static struct mmc_blk_data *mmc_blk_allo
 {
 	struct mmc_blk_data *md;
 	int devidx, ret;
+	unsigned long cap;
 
 	devidx = find_first_zero_bit(dev_use, MMC_NUM_MINORS);
 	if (devidx >= MMC_NUM_MINORS)
@@ -356,10 +357,19 @@ static struct mmc_blk_data *mmc_blk_allo
 		sprintf(md->disk->disk_name, "mmcblk%d", devidx);
 		sprintf(md->disk->devfs_name, "mmc/blk%d", devidx);
 
-		md->block_bits = card->csd.read_blkbits;
+		if (card->csd.read_blkbits > 9) {
+			md->block_bits = 9;
+
+			cap = card->csd.capacity <<
+				(card->csd.read_blkbits - 9);
+		}
+		else {
+			md->block_bits = card->csd.read_blkbits;
+			cap = card->csd.capacity;
+		}
 
 		blk_queue_hardsect_size(md->queue.queue, 1 << md->block_bits);
-		set_capacity(md->disk, card->csd.capacity);
+		set_capacity(md->disk, cap);
 	}
  out:
 	return md;
@@ -373,7 +383,7 @@ mmc_blk_set_blksize(struct mmc_blk_data 
 
 	mmc_card_claim_host(card);
 	cmd.opcode = MMC_SET_BLOCKLEN;
-	cmd.arg = 1 << card->csd.read_blkbits;
+	cmd.arg = 1 << ((card->csd.read_blkbits > 9) ? 9 : card->csd.read_blkbits);
 	cmd.flags = MMC_RSP_R1;
 	err = mmc_wait_for_cmd(card->host, &cmd, 5);
 	mmc_card_release_host(card);