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

[Mark Lord <liml@rtr.ca>]

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.

Cheers