From: Rajagopal Venkat <rajagopal.venkat@linaro.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: myungjoo.ham@samsung.com, rjw@sisk.pl,
Kevin Hilman <khilman@linaro.org>,
linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] PM / devfreq: tie suspend/resume to runtime-pm
Date: Fri, 22 Mar 2013 14:35:07 +0530 [thread overview]
Message-ID: <CA+Z25wXYprpAOChV2P1vfbTgUyd7Te5s3RCmTLLaez6qiTx5GA@mail.gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1303211101530.1899-100000@iolanthe.rowland.org>
On 21 March 2013 20:32, Alan Stern <stern@rowland.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
next prev parent reply other threads:[~2013-03-22 9:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-21 13:28 [PATCH 0/2] Add devfreq runtime pm support Rajagopal Venkat
2013-03-21 13:28 ` [PATCH 1/2] PM / devfreq: Fix compiler warnings Rajagopal Venkat
2013-03-21 13:28 ` [PATCH 2/2] PM / devfreq: tie suspend/resume to runtime-pm Rajagopal Venkat
2013-03-21 15:02 ` Alan Stern
2013-03-22 9:05 ` Rajagopal Venkat [this message]
2013-03-22 17:34 ` Kevin Hilman
2013-03-25 6:13 ` Rajagopal Venkat
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