Worrisome IDE PIO transfers...

[Jeff Garzik]

Looking at the function that is used to transfer data when in PIO mode...

void taskfile_output_data (ide_drive_t *drive, void *buffer, u32 wcount)
{
        if (drive->bswap) {
                ata_bswap_data(buffer, wcount);
                HWIF(drive)->ata_output_data(drive, buffer, wcount);
                ata_bswap_data(buffer, wcount);
        } else {
                HWIF(drive)->ata_output_data(drive, buffer, wcount);
        }
}

Swapping the data in-place is very, very wrong...   you don't want to be 
touching the data that userspace might have mmap'd ...  Additionally, 
byteswapping back and forth for each PIO sector chews unnecessary CPU.

Seems to me the architecture's OUTS[WL] hook (or a new, similar hook) 
that swaps as it writes would be _much_ preferred, and eliminate this 
possible data corruption issue.

	Jeff




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