Re: [PATCH] libata: add support for READ/WRITE LONG

[Jeff Garzik <jgarzik@pobox.com>]

Mark Lord wrote:
> Jeff Garzik wrote:
>> Alan Cox wrote:
>>>>     I think it only requires the *host* to drop to PIO0 timings.  In 
>>>> which case it should be achievable w/o libata modification -- if the 
>>>> driver has to "snoop" command and turn off prefetch, why not switch 
>>>> to PIO0 temporarily?
>>>
>>> This isn't a big issue. Eventually we have to support sending speed
>>> change commands and once we do that the caller will be able to switch to
>>> PIO0 and back again.
>>
>> We should be pretty close to that.  One of the bigger blockages is 
>> needing to stop (freeze) all ports, before performing an out-of-band 
>> SET FEATURES and related tuning.
> 
> For this particular feature, READ/WRITE LONG,
> none of this is actually necessary in practice on common controllers.
> 
> I've tested ATA1 and newer PATA drives, and various SATA drives
> with these commands without bothering to drop to PIO0,
> and none of them had issues.

I wasn't implying a blockage of your patch, just describing a general 
problem within libata.

	Jeff