linux-kernel - Re: [PATCH 0/8] Cpufreq, cpu hotplug, suspend/resume related fixes

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Message-ID: <51E6BD0E.1020101@linux.vnet.ibm.com>
Date:	Wed, 17 Jul 2013 21:19:34 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	Toralf Förster <toralf.foerster@....de>,
	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	viresh.kumar@...aro.org, robert.jarzmik@...el.com,
	durgadoss.r@...el.com, tianyu.lan@...el.com,
	lantianyu1986@...il.com, dirk.brandewie@...il.com,
	stern@...land.harvard.edu, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/8] Cpufreq, cpu hotplug, suspend/resume related fixes

On 07/17/2013 08:57 PM, Toralf Förster wrote:
> On 07/16/2013 11:32 PM, Rafael J. Wysocki wrote:
>> On Tuesday, July 16, 2013 05:15:14 PM Toralf Förster wrote:
>>> On 07/12/2013 12:23 AM, Srivatsa S. Bhat wrote:
>>>> On 07/12/2013 04:03 AM, Rafael J. Wysocki wrote:
>>>>> On Friday, July 12, 2013 03:45:17 AM Srivatsa S. Bhat wrote:
>>>>>>
>>>>>> Hi,
>>>>>
>>>>> Hi,
>>>>>
>>>>>> Commit a66b2e (cpufreq: Preserve sysfs files across suspend/resume) caused
>>>>>> some subtle regressions in the cpufreq subsystem during suspend/resume.
>>>>>> This patchset is aimed at rectifying those problems, by fixing the regression
>>>>>> as well as achieving the original goal of that commit in a proper way.
>>>>>>
>>>>>> Patch 1 reverts the above commit, and is CC'ed to stable.
>>>>>>
>>>>>> Patches 2 - 5 reorganize the code and have no functional impact, and can go
>>>>>> in as general cleanups as well. This reorganization builds a base that the
>>>>>> rest of the patches will make use of.
>>>>>>
>>>>>> Patch 6 and 7 add a mechanism to perform light-weight init/tear-down of CPUs
>>>>>> in the cpufreq subsystem and finally patch 8 uses it to preserve sysfs files
>>>>>> across suspend/resume.
>>>>>>
>>>>>> All the patches apply on current mainline.
>>>>>>
>>>>>>
>>>>>> Robert, Durgadoss, it would be great if you could try it out and see if it works
>>>>>> well for your usecase. I tested it locally and cpufreq related files did retain
>>>>>> their permissions across suspend/resume. Let me know if it works fine in your
>>>>>> setup too.
>>>>>>
>>>>>> And I'd of course appreciate to hear from Dirk, Tianyu and Toralf to know
>>>>>> whether their systems work fine after:
>>>>>> a. applying only the first commit (this is what gets backported to stable)
>>>>>> b. applying all the commits
>>>>>>
>>>>>> (Note: I had to use Michael's fix[1] to avoid CPU hotplug deadlock while
>>>>>> testing this patchset. Though that patch also touches cpufreq subsystem, it
>>>>>> doesn't affect this patchset in any way and there is absolutely no dependency
>>>>>> between the two in terms of code. That fix just makes basic CPU hotplug work
>>>>>> without locking up on current mainline).
>>>>>>
>>>>>> [1]. https://lkml.org/lkml/2013/7/10/611
>>>>>>
>>>>>>
>>>>>> Thank you very much!
>>>>>
>>>>> Thanks Srivatsa!
>>>>>
>>>>> I'm going to take [1/8] for 3.11 and queue up the rest for 3.12 if people don't
>>>>> hate them.  This way we'll have some more testing coverage before they reach
>>>>> the mainline hopefully.
>>>>>
>>>
>>> On 07/16/2013 01:25 AM, Rafael J. Wysocki wrote:> On Monday, July 15, 2013 07:38:02 PM Toralf Förster wrote:
>>>> Sorry, I have no idea what 1#8 means.
>>>
>>> sry - here again with full quote of the email :
>>>
>>> I applied patch [1/8] on top of v3.11-rc1-8-g47188d3 passes two s2ram/wakeup
>>> cycles fine and crashed the system at the 3rd attempt / one times just at
>>> the 4th (blinking power led, no sysrq, ...).
>>>
>>> Applying patch 1-8 on top of that tree differs in that way that it
>>> crashes now the system even at the 1st attempt or at least at the 2nd
>>>
>>> My hardware is a ThinkPad T420 with latest BIOS and a 32 bit stable
>>> Gentoo Linux - FWIW .config attached.
>>
>> I think you'll need the fixes first, basically [1/8] from this series and
>> this: https://patchwork.kernel.org/patch/2827512/ .
>>
>> Please try to run with these two things applied only and see how that goes.
>>
>> Thanks,
>> Rafael
>>
>>
> That was it.
> 
> Applying https://patchwork.kernel.org/patch/2827512/ and then patch
> [1/8] on top of v3.11-rc1-8-g47188d3 works fine and solved the reported
> issue.
> 
> Furthermore applying patches 2-8 works too - suspend/wakeup works fine
> and frequencies are scaled right after wakeup at the T420.
> 

Phew! Finally :-)

Thank you for all your testing efforts!
 
Regards,
Srivatsa S. Bhat

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