Re: SATA DMA problem (sata_uli)

[Jeff Garzik <jgarzik@pobox.com>]

Tejun Heo wrote:
> Jeff Garzik wrote:
> > 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.
>
> Just another data point.  The same problem is reported by bug #7590.
>
> http://bugzilla.kernel.org/show_bug.cgi?id=7590
>
> Is somebody brewing a patch?

Not to my knowledge.  Did you just volunteer?  ;-)

/me runs...

	Jeff



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