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libata-sff: fix 32-bit PIO ATAPI regression 

Commit 871af1210f (libata: Add 32bit
PIO support) has caused all kinds of errors on the ATAPI devices, so
it has been empirically proven that one shouldn't try to read/write
an extra data word when a device is not expecting it already. "Don't
do it then"; however, still use a chance to do 32-bit read/write one
last time when there are exactly 3 trailing bytes.

Oh, and stop pointlessly swapping the bytes to and fro on big-endian
machines by using io*_rep() accessors which shouldn't byte-swap.

This patch should fix the kernel.org bug #12609.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
Sergei Shtylyov 2009-02-15 23:24:24 +04:00 committed by Jeff Garzik
parent d2f8d7ee1a
commit d1b3525b41
1 changed files with 21 additions and 7 deletions
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28
drivers/ata/libata-sff.c
View File

@ -773,18 +773,32 @@ unsigned int ata_sff_data_xfer32(struct ata_device *dev, unsigned char *buf,
else
iowrite32_rep(data_addr, buf, words);
/* Transfer trailing bytes, if any */
if (unlikely(slop)) {
__le32 pad;
unsigned char pad[4];
/* Point buf to the tail of buffer */
buf += buflen - slop;
/*
* Use io*_rep() accessors here as well to avoid pointlessly
* swapping bytes to and fro on the big endian machines...
*/
if (rw == READ) {
pad = cpu_to_le32(ioread32(ap->ioaddr.data_addr));
memcpy(buf + buflen - slop, &pad, slop);
if (slop < 3)
ioread16_rep(data_addr, pad, 1);
else
ioread32_rep(data_addr, pad, 1);
memcpy(buf, pad, slop);
} else {
memcpy(&pad, buf + buflen - slop, slop);
iowrite32(le32_to_cpu(pad), ap->ioaddr.data_addr);
memcpy(pad, buf, slop);
if (slop < 3)
iowrite16_rep(data_addr, pad, 1);
else
iowrite32_rep(data_addr, pad, 1);
}
words++;
}
return words << 2;
return (buflen + 1) & ~1;
}
EXPORT_SYMBOL_GPL(ata_sff_data_xfer32);