linux-kernel - Re: acpi-test tree on eeepc: EC error message on second resume

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Message-ID: <48F0ED3A.9010001@tuffmail.co.uk>
Date:	Sat, 11 Oct 2008 19:15:22 +0100
From:	Alan Jenkins <alan-jenkins@...fmail.co.uk>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	Alexey Starikovskiy <astarikovskiy@...e.de>,
	linux acpi <linux-acpi@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: acpi-test tree on eeepc: EC error message on second resume

Rafael J. Wysocki wrote:
> On Saturday, 11 of October 2008, Alan Jenkins wrote:
>   
>> Rafael J. Wysocki wrote:
>>     
>>> On Saturday, 11 of October 2008, Alan Jenkins wrote:
>>>   
>>>       
>>>> I've just run an acpi-test kernel on my EeePC and noticed a new issue. 
>>>> It seems to be caused (or revealed) by the EC interrupt transaction patch.
>>>>
>>>> On the second suspend/resume cycle, I see a kernel error message.
>>>>
>>>> [   78.747707] ACPI: Waking up from system sleep state S3
>>>> [   79.330001] ACPI: EC: input buffer not empty, aborting transaction
>>>> [   79.423327] ACPI: EC: non-query interrupt received, switching to
>>>> interrupt mode
>>>>
>>>> I still don't see any issues in the code.  I'll try getting a DEBUG
>>>> trace to see the EC interrupts.  Any other suggestions?
>>>>     
>>>>         
>>> Not really, but is this reproducible?  I mean, does it happen always on the
>>> second resume and does it happen on every next resume after the first one?
>>>
>>> Thanks,
>>> Rafael
>>>   
>>>       
>> Ah.  No, I spoke to soon.  It happened on the second resume the first
>> two times I tried it.  But this third time with DEBUG enabled, it
>> happened on the first suspend/resume.
>>
>> And it doesn't happen on all subsequent resumes either.  I've had one
>> suspend/resume without the error, just after a suspend/resume with the
>> error.
>>
>> So it's not deterministic, but it is easy to reproduce.
>>     
>
> I can't reproduce this on any hardware available to me, so far.
>
> Is this related to any other problem, like things not working etc.?
>   

Nope, just an error message.  Though I do worry that "random EC
transaction aborts during resume" could hit something important
somewhere, sometime.

I think I found the problem.  The "input buffer empty" wait depends on
"interrupt mode" to work properly, and we don't immediately enable the
interrupt on resume.  The wait should have a polling fallback anyway, to
be consistent with the other transaction waits.

Alan
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