linux-kernel - Re: [PATCH] thermal/cpu_cooling: remove local cooling state variable

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Date:	Mon, 3 Aug 2015 12:28:39 -0700
From:	Radivoje Jovanovic <radivoje.jovanovic@...ux.intel.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Punit Agrawal <punit.agrawal@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM <linux-pm@...r.kernel.org>,
	Zhang Rui <rui.zhang@...el.com>,
	Eduardo Valentin <edubezval@...il.com>,
	Radivoje Jovanovic <radivoje.jovanovic@...el.com>
Subject: Re: [PATCH] thermal/cpu_cooling: remove local cooling state
 variable

On Mon, 3 Aug 2015 08:43:25 +0530
Viresh Kumar <viresh.kumar@...aro.org> wrote:

> On 01-08-15, 17:04, Viresh Kumar wrote:
> > On 31-07-15, 08:30, Radivoje Jovanovic wrote:
> 
> > > I agree with you that this patch is trivial for the current
> > > implementation since the notifier, as it is currently, will
> > > enforce cpu_cooling policy change at every CPUFREQ_ADJUST which
> > > would cause problems in our current implementation. In our
> > > implementation there is a cpufreq driver that will also change
> > > policies during CPUFREQ_ADJUST, once the request comes from the
> > > underlying FW so there would be a fight who gets there first
> > > since cpu_cooling will change the policy in CPUFREQ_ADJUST
> > > notifier_chain and the driver would do the same thing.
> 
> Okay, I had a detailed look this morning. cpufreq-notifier is designed
> this way that policy->max can be updated by drivers.. So, that's fine.
> 
> Now coming to your problem. So, there are two users: fw and thermal,
> which can affect policy->max. Now, both of them need to respect the
> limits set by others and only decrease policy->max from the notifier
> if it doesn't suit them.
> 
> I think it should work pretty well, unless you know you have triggered
> a corner case somewhere, that I am not able to imagine.
> 
> Please let me know in case I am wrong.
>
I will port the upstream driver to our platfrom, test for all corner
cases and update this thread once I have the data
Thank you for all the help
 

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