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

[Mark Lord <liml@rtr.ca>]

Mark Lord wrote:
> Tejun Heo wrote:
>> So, this is specific to SATA (the host side at least) piix && PIO READ,
>> right?  I think we can fit this code nicely into
>> piix_sata_error_handler() if we make sure that it triggers under the
>> right condition - after a PIO READ command fails due to HSM violation
>> caused by stuck DRQ.
> 
> Yeah, so far it's just PIO FROM DEVICE on a "SATA" device on ata_piix.
> It *may* be more widespread than that, but we'll have to test some others.

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.