On Sun, 8 Feb 2009, Sergei Shtylyov wrote: > Commit 871af1210f13966ab911ed2166e4ab2ce775b99d (libata: Add 32bit PIO support) > caused all kind of errors on the ATAPI devices, so it's been empirically proven > that one shouldn't read/write an extra data word when a device isn't expecting > it already. "Don't do it then"; however still taking a chance to use 32-bit I/O > one last time when there are exactly 3 trailing bytes. Oh, and stop pointless > swapping bytes to and fro as well by using io*_rep() which shouldn't byte-swap. > > This should fix the kernel.org bug #12609. > > --- > This is hopefully better replacement for Hugh Dickins most recent patch > (http://marc.info/?l=linux-ide&m=123352294619281)... Yes, looks nice, and works for me. My only criticism would be, minor issue unchanged by your patch, that actually "slop" isn't unlikely enough to deserve an "unlikely" - slop of 1 or 3 is unlikely, but slop of 2 is quite common. Hugh > > drivers/ata/libata-sff.c | 23 ++++++++++++++++------- > 1 files changed, 16 insertions(+), 7 deletions(-) > > Index: linux-2.6/drivers/ata/libata-sff.c > =================================================================== > --- linux-2.6.orig/drivers/ata/libata-sff.c > +++ linux-2.6/drivers/ata/libata-sff.c > @@ -773,18 +773,27 @@ unsigned int ata_sff_data_xfer32(struct > 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; > 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); > -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
