linux-kernel - Re: [PATCH 2/2] PM / devfreq: tie suspend/resume to runtime-pm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 22 Mar 2013 14:35:07 +0530
From:	Rajagopal Venkat <rajagopal.venkat@...aro.org>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	myungjoo.ham@...sung.com, rjw@...k.pl,
	Kevin Hilman <khilman@...aro.org>,
	linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] PM / devfreq: tie suspend/resume to runtime-pm

On 21 March 2013 20:32, Alan Stern <stern@...land.harvard.edu> wrote:
> On Thu, 21 Mar 2013, Rajagopal Venkat wrote:
>
>> Allow device devfreq to be suspend/resume automatically with
>> runtime pm suspend/resume. The devfreq drivers should be least
>> cared when to suspend/resume the devfreq.
>>
>> pm_runtime_suspend(dev) will first suspend device devfreq(if available)
>> before device is suspended from runtime pm core.
>>
>> pm_runtime_resume(dev) will resume device devfreq(if available) after
>> device is resumed from runtime pm core.
>
> Aren't these backward?  The device continues to need its clocks and
> frequency settings until _after_ it has been suspended.  Similarly, it
> needs them to be available _before_ it resumes.
>

To clarify, devfreq suspend/resume means suspend/resume of load
monitoring of a device. The clocks and other resources are still taken
care by the devfreq driver runtime-pm callbacks. The devfreq must be
suspended _before_ runtime-pm suspend callback in order to stop load
monitoring while device is suspending. Similarly devfreq resume should
happen _after_ runtime-pm resume callback.

Just realised both devfreq suspend/resume are done _before_ invoking
runtime-pm callbacks. I will fix this up. Thanks.


> Alan Stern
>



-- 
Regards,
Rajagopal
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/