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Commit d1b3525b authored by Sergei Shtylyov's avatar Sergei Shtylyov Committed by Jeff Garzik
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libata-sff: fix 32-bit PIO ATAPI regression 



Commit 871af121 (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: default avatarSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent d2f8d7ee

drivers/ata/libata-sff.c

+21 −7
Original line number Diff line number Diff line
@@ -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);