Commit 6fe9febb authored by Pierre Ossman's avatar Pierre Ossman Committed by Russell King
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[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: default avatarPierre Ossman <drzeus@drzeus.cx>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent d773d725
......@@ -319,52 +319,11 @@ 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) {
......
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