releases/2.6.17.14/mmc-always-use-a-sector-size-of-512-bytes.patch

From stable-bounces@linux.kernel.org Sat Sep 16 21:06:20 2006
Message-ID: <450CC959.9070709@gentoo.org>
Date: Sun, 17 Sep 2006 00:04:41 -0400
From: Pierre Ossman <drzeus@drzeus.cx>
To: stable@kernel.org
Cc: drzeus@drzeus.cx
Subject: MMC: Always use a sector size of 512 bytes

From: Pierre Ossman <drzeus@drzeus.cx>

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>

---
 drivers/mmc/mmc_block.c |   49 +++---------------------------------------------
 1 file changed, 4 insertions(+), 45 deletions(-)

--- linux-2.6.17.13.orig/drivers/mmc/mmc_block.c
+++ linux-2.6.17.13/drivers/mmc/mmc_block.c
@@ -325,52 +325,11 @@ static struct mmc_blk_data *mmc_blk_allo
 	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) {