Re: 2.6.32: Promise UDMA33 card refuses to work in UDMA mode

[Jeff Garzik <jeff@garzik.org>]

On 01/04/2010 12:30 PM, Russell King wrote:
> On Mon, Jan 04, 2010 at 12:27:54PM -0500, Jeff Garzik wrote:
>> On 01/04/2010 12:02 PM, Alan Cox wrote:
>>>> (1b)  The solution for MMIO controllers is a bit more complex:  replace
>>>> the dummy AltStatus register read with something else.
>>>
>>> If we had any SFF PATA controllers using MMIO. I can't find any. SATA is
>>> different anyway. In fact we probably want to avoid such delays on a pure
>>> SATA controller.
>>
>> Early SATA controllers are just PATA controllers in disguise.  All SFF
>> controllers want that 400ns delay.  The 400ns delay should -not- be
>> avoided.
>
> Note that ICH5 SATA is SFF, which only offers non-MMIO addressing; the
> change I made is running there just fine:

Yes, your change should be fine for all non-MMIO SFF controllers, SATA 
or PATA.

The AltStatus read is simply a dummy read, for MMIO controllers, to 
ensure the previously-written taskfile registers make it to the 
controller before the ndelay() begins execution.

	Jeff