Re: SATA DMA problem (sata_uli)

[Jeff Garzik <jgarzik@pobox.com>]

Alan wrote:
> > I tracked it down to one of the drives being forced into PIO4 mode
> > rather than UDMA mode; dmesg bits:
> > ata4.00: ATA-7, max UDMA/133, 586072368 sectors: LBA48 NCQ (depth 0/32)
> > ata4.00: ata4: dev 0 multi count 16
> > ata4.00: simplex DMA is claimed by other device, disabling DMA
>
> Your ULi controller is reporting that it supports UDMA upon only one
> channel at a time. The kernel is honouring this information. The older
> ULi (was ALi) PATA devices report simplex but let you turn it off so see 
> if the following does the trick. Test carefully as always with disk driver
> changes.
>
> (Jeff probably best to check the docs before merging this but I believe
> it is sane)
>
> Signed-off-by: Alan Cox <alan@redhat.com>

My Uli SATA docs do not appear to cover the bmdma registers :(  Only the 
PCI config registers.

But regardless, I think the better fix is to never set ATA_HOST_SIMPLEX 
if ATA_FLAG_NO_LEGACY is set.

None of the SATA controllers I've ever encountered has been simplex.

	Jeff



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