Re: [PATCH] ACPI : Avoid bogus timeout about SMbus check

[Alexey Starikovskiy <astarikovskiy@suse.de>]

Hi Oldrich,

It might happen that you too have GPE storm on your machine. The patch
to workaround it was placed in 9998 and 10724 bug reports.
So, for a start you could check if the last patch in 9998 makes any difference.
We probably could drop wait_event_timeout() as the last resort.

Regards,
Alex.

Oldrich Jedlicka wrote:
> On Thursday 04 of September 2008 at 14:18:20, Andi Kleen wrote:
>> On Tue, Aug 26, 2008 at 01:57:34PM +0800, Zhao Yakui wrote:
>>> Subject: ACPI: Avoid bogus timeout about SMbus check
>>>
>>> >From :  Zhao Yakui <yakui.zhao@intel.com>
>>>
>>> In the function of wait_transaction_complete when the timeout happens,
>>> OS will try to check the status of SMbus again. If the status is what OS
>>> expected, it will be regarded as the bogus timeout. Otherwise it will be
>>> treated as ETIME.
>>>
>>> http://bugzilla.kernel.org/show_bug.cgi?id=10483
>> I added it for 2.6.27 thanks (since it seems to be a regression)
> 
> Hi all,
> 
> the problem in bug 10483 isn't solved, unfortunately the patch applied to 
> 2.6.27 isn't the one I tested.
> 
> The problem I face is that wait_transaction_complete() in sbshc.c doesn't take 
> at most "timeout" time (=one second), but it rather often takes very long 
> time to complete on my system (several minutes) - notebook Acer TravelMate 
> 4502WLMi.
> 
> To describe the problem I need to go into wait_event_timeout() macro as used 
> in wait_transaction_complete(): it first calls the user method 
> smb_check_done() to check if the loop should end and if not, it waits for at 
> most "timeout" time. The wait can be woken-up by a wake_up() method and if 
> so, it remembers the remaining "timeout", repeats the call to user method 
> smb_check_done() and possibly continues with wait (with the 
> remaining "timeout"). This is done in a loop.
> 
> Now my problem: the wait_event_timeout() loop takes several minutes instead of 
> one second (as specified by the parameter "timeout"). The reason for that - as 
> I think - is this:
> 
>   1. The smb_check_done() method called each loop takes some time to execute, 
> but this time is not included into the overall timeout.
>   2. The wait_event_timeout() is woken-up by smbus_alarm() very early each 
> loop, so the remaining "timeout" gets lower very slow (I think it is so, but 
> I haven't verified this hypothesis yet).
> 
> So my question is what I shoud do now? If you want to see some logs (and the 
> original patch), please go to my bug report:
> 
>   http://bugzilla.kernel.org/show_bug.cgi?id=10483
> 
> Thanks.
> 
> Note: I'm building my house after my normal work, so I don't have much time 
> left, but I will do my best to try whatever you suggest. And sorry for my 
> english :-)
> 
> Regards,
> Oldrich.
>