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