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    SubjectRe: SATA DMA problem (sata_uli)
    Jeff Garzik wrote:
    > 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 <>
    >>> 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?
    > Not to my knowledge. Did you just volunteer? ;-)
    > /me runs...

    I'm just gonna ack Alan's patch.

    * ATA_FLAG_NO_LEGACY is not really used widely (and thus LLDs don't set
    it rigorously). I think it should be removed once we get initialization
    model right.

    * I'm really reluctant to add more LLD-specific knowledge into libata
    core. We're already carrying too much due to the current init model
    (libata should initialize host according to probe_ent, so many
    weirdities should be represented in probe_ent in a form libata core

    * The idea of clearing simplex for unknown controllers scares the hell
    out of me. where's mummy...

    So, I'll ask bug reporter of #7590 to test it.

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      Last update: 2006-12-20 03:47    [W:0.088 / U:12.312 seconds]
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