[Devel] Re: unexpected scsi timeout

[Tejun Heo]

Vasily Averin wrote:
> Albert Lee wrote:
>>>> Vasily Averin wrote:
>>>>> I've noticed that some scsi commands for DVD-drive attached to pata_via
>>>>> successfully finishes without any delays but reports about TIMEOUT condition. It
>>>>> happens because of ATA_ERR bit is set in status register. As result for each
>>>>> command  Error Handler thread awakened, requests sense buffer and go to sleep again.
>>>> Need more info.  Please post boot dmesg and the result of 'lspci -nn'
>>>> and 'hdparm -I /dev/srX' and when such errors occur.
>> Your log looks ok. It's normal for TEST_UNIT_READY to return ATA_ERR when no disc
>> inside and libata EH triggered to request sense.
> 
> It's a bit strange for me, IMHO other scsi drivers requests sense buffer without
> EH thread assistance.
> Currently we know that ATA_ERR can be returned; it is not error, but one of
> expected responses. Why we cannot request sense without EH? I would like to
> understand is it implementation drawback or I missed something probably?

That was a design choice.  It's easier to implement that way.

-- 
tejun