linux-kernel - Re: [PATCH V5 0/7] cpufreq: suspend early/resume late: dpm

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Message-Id: <BEC64F5C-76E8-40C3-81BE-59096C3838F3@linaro.org>
Date:	Thu, 20 Feb 2014 07:20:35 +0530
From:	Linaro <viresh.kumar@...aro.org>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Nishanth Menon <nm@...com>, Kgene Kim <kgene.kim@...sung.com>,
	"jinchoi@...adcom.com" <jinchoi@...adcom.com>,
	Lan Tianyu <tianyu.lan@...el.com>,
	Sebastian Capella <sebastian.capella@...aro.org>,
	Jonghwan Choi <jhbird.choi@...sung.com>
Subject: Re: [PATCH V5 0/7] cpufreq: suspend early/resume late: dpm_{suspend|resume}()



> On 20-Feb-2014, at 7:19 am, Linaro <viresh.kumar@...aro.org> wrote:
> 
> 
> 
>>> On 19-Feb-2014, at 10:56 pm, Stephen Warren <swarren@...dotorg.org> wrote:
>>> 
>>>> On 02/18/2014 09:15 PM, Viresh Kumar wrote:
>>>>> On 19-Feb-2014 1:48 AM, "Stephen Warren" <swarren@...dotorg.org> wrote:
>>>>> 
>>>>>> On 02/17/2014 02:20 AM, Viresh Kumar wrote:
>>>>>> On 15 February 2014 05:33, Stephen Warren <swarren@...dotorg.org> wrote:
>>>>>> On 02/14/2014 03:23 PM, Rafael J. Wysocki wrote:
>>>>> 
>>>>>>> Well, it would be good to verify which part, then.
>>>>>> 
>>>>>> Patch 2/7 appears to stop that message from being printed during
>>>>>> suspend, and perhaps reduce the number of times it's printed during
>>>>>> resume. Patch 7/7 stops the message being printed at all.
>>>>>> 
>>>>>> Looking at patch 7, I wonder if it's simply because tegra_target() was
>>>>>> modified never to return -EBUSY, so the bug is still there, but it's
>>>>>> just been hidden.
>>>>> 
>>>>> No, the bug is removed now. Its hidden in current linus/master :)
>>>> 
>>>> I'm not sure what that means; I still see the message:
>>> 
>>> I have given a better reply in one of the earlier mails in this thread.
>>> And skipped a more elaborative reply now.
>>> 
>>> So this failure was always there since long time, as you disable your
>>> target() fn early in suspend. But the message wasn't printed earlier.
>>> 
>>> A recently added core patch started printing this, so not a new bug.
>>> But this series fixes suspend resume completely and you wouldn't see it
>>> anymore.
>> 
>> OK, so I suppose we have two options:
>> 
>> a) Just ignore the kernel error spew since it's a known issue.
>> 
>> b) If I make the Tegra driver return 0 rather than -EBUSY, would that
>> work? It would certainly silence the error. However, I wonder if it
>> would cause the cpufreq core to get out of sync with HW; the core would
>> think that it'd set some frequency, which the driver ignored, and if it
>> later wanted to switch frequency, the call might get skipped because the
>> core thought the HW was already set to that frequency?
> 
> Option is the one you need.

Option a..--
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