linux-kernel - Re: [PATCH] cpufreq: skip cpufreq resume if it's not suspended

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Date:   Thu, 15 Feb 2018 23:06:39 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Saravana Kannan <skannan@...eaurora.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>, Bo Yan <byan@...dia.com>,
        sgurrappadi@...dia.com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: skip cpufreq resume if it's not suspended

On Thursday, February 15, 2018 10:27:10 PM CET Saravana Kannan wrote:
> On 02/05/2018 01:05 AM, Viresh Kumar wrote:
> > On 05-02-18, 09:50, Rafael J. Wysocki wrote:
> >> By design (which I admit may be confusing) it should be fine to call
> >> dpm_resume_end() after a failing dpm_suspend_start(), whatever the reason
> >> for the failure is.  cpufreq_suspend/resume() don't take that into account,
> >> everybody else does.
> >
> > Hmm, I see. Can't do much then, just fix the only broken piece of code :)
> >
> 
> Sorry for the late reply, this email didn't get filtered into the right 
> folder.
> 
> I think the design of dpm_suspend_start() and dpm_resume_end() generally 
> works fine because we seem to keep track of what devices have been 
> suspended so far (in the dpm_suspended_list) and call resume only of 
> those. So, why isn't the right fix to have cpufreq get put into that 
> list?

Because it is more complicated?

> Instead of just always call it on the resume path even if it 
> wasn't suspended? That seems to be the real issue.
> 
> So, we should either have dpm_suspend/resume() have a flag to keep track 
> of if cpufreq_suspend/resume() was called and make sure they are called 
> in proper pairs.

Why?

> Or have cpufreq register in a way that gets it put in 
> the suspend/resume list.
> 
> I'd still like to NACK this change.

It's gone in already, sorry.