Re: libata fails to recover from HSM violation involving DRQ status

[Mark Lord <liml@rtr.ca>]

Mark Lord wrote:
> Mark Lord wrote:
>
>> I retested this again today on my new pure-SATA notebook with ata_piix.
>> In this case, the DRQ drain is not necessary, but also doesn't harm 
>> anything.
>> Tested it both ways.  This is with a Hitachi HTS541612J9SA00 SATA drive.
>>
>> The original fault was on ata_piix SATA, with some kind of external
>> bridge (on the motherboard) to a Seagate PATA drive.  Sometime in the
>> next few days I'll have the exact same drive, but with a SATA interface,
>> and we'll try that in the pure-SATA situation.
>>
>> This will tell us whether it's the bridge, or the drive, that was the 
>> issue.
>>
>> The fix remains the same: drain the data fifo when DRQ is left high.
> 
> Okay, I finally got round to testing this with the new pure-SATA
> notebook I have here.  Same problem:  without draining the DRQ fifo,
> the system *never* recovers.
> 
> But with the patch to drain DRQ, all is well.  That patch is now a keeper
> for my own kernels.  Tejun, did you want to cook up a better-placed variant
> of it for mainline?  I'm away for a few days now..

A note for anyone confused by my two postings above:
The DRQ drain *is* needed for the Seagate notebook drives (PATA/SATA),
but not for the Hitachi notebook SATA drive I also have here.

Cheers