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SubjectRe: SATA DMA problem (sata_uli)
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 <>
> 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.

Is somebody brewing a patch?

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