Re: cached PCS

[Tejun Heo <htejun@gmail.com>]

Jeff Garzik wrote:
> Tejun Heo wrote:
>> Jeff Garzik wrote:
>>> Tejun Heo wrote:
>>>> Jeff Garzik wrote:
>>>>> Tejun Heo wrote:
>>>>>> Jeff Garzik wrote:
>>>>>>> can you resurrect your cached PCS patch?
>>>>>>>
>>>>>>> 2.6.18-rc didn't fix the ghost device and long boot delay 
>>>>>>> problems for everybody.
>>>>>>
>>>>>> The cached PCS patch was to fix device detection failure on some 
>>>>>> ICH5s where PCS is cleared while probing the first port.  
>>>>>> Remaining ghost device and long boot delay are fixed by honor-PCS 
>>>>>> patch.  Do you want me to resurrect both?
>>>>>
>>>>> hrm.  Maybe just honor-PCS?
>>>>
>>>> Yeap, we need to verify whether the less-jealous-PCS-update patch 
>>>> cured the ICH5 problem.
>>>
>>> If you are talking about the patch currently in 2.6.18-rc, I got 
>>> several ACKs that it fixed their problems.
>>>
>>> But OTOH, there was also
>>> http://marc.theaimsgroup.com/?t=115346292700002&r=1&w=2
>>
>> I was talking about bugzilla bug #6724.
>>
>> http://bugzilla.kernel.org/show_bug.cgi?id=6724
>>
>> It was a weird case of ICH5 clearing PCS present bits while the first 
>> port is being probed.  The clearing happens during actual probe, that 
>> is, the bits look okay till the end of the first prereset() but on 
>> entry to prereset() for the second port, enabled bits are gone.  IIRC, 
>> bug#6724 is different from all other reports.
>>
>> I asked the reporter to test 2.6.18-rc4 and see whether the problem is 
>> gone with new PCS handling.  I'm a bit skeptical about the result.  If 
>> the problem remains with 2.6.18-rc4, we'll need that cached PCS to 
>> solve that particular case.
>>
>> BTW, do you know what Keith Owen's chipset was?
> 
> (Keith CC'd)
> 
> I didn't see lspci output, but it looks like ICH5 from his drivers/ide 
> dmesg output.
> 
> Did you look at some of the other messages?  He provided some debug 
> traces in follow-up messages.

Yes, I have and I can't think of any other way than ignoring PCS to work 
around the problem.  If we set IGNORE_PCS for ich5 sata then we can also 
forget about cached PCS which is for ich5 sata.  But, we might see ghost 
device detection and accompanying long delays.

For ich 6/7/8, your recent change and honor-pcs patch should do the job. 
  For ICH5, well...  Just set IGNORE_PCS and wait for bug reports?

-- 
tejun