linux-kernel - Re: [PATCH 4/4] cpu_cooling: Drop static-power related stuff

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Date:   Tue, 21 Nov 2017 18:00:07 +0000
From:   Javi Merino <javi.merino@...nel.org>
To:     Eduardo Valentin <edubezval@...il.com>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        Lukasz Luba <llu.ker.dev@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Ionela Voinescu <ionela.voinescu@....com>,
        Punit Agrawal <punit.agrawal@....com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Amit Daniel Kachhap <amit.kachhap@...il.com>,
        Zhang Rui <rui.zhang@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        Lukasz Luba <lukasz.luba@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] cpu_cooling: Drop static-power related stuff

Hi,

On Tue, Nov 21, 2017 at 08:57:06AM -0800, Eduardo Valentin wrote:

[snip]

> As I said before, the minimal you guys (ARM and Linaro) can do is to at
> least upstream the Juno code! as a reference. Come on guys?  what is
> preventing you to upstream Juno model?

As Ionela pointed out earlier in the thread, the cpufreq driver for Juno
was not acceptable for mainline because it used platform specific code.
When it was converted to cpufreq-dt, the static power was left behind
because it can't be represented in device tree.  This is because there
isn't a function that works for every SoC, different process nodes
(among other things) will need different functions.  So it can't be just
a bunch of coefficients in DT, we need a function.  Hence the callback.

In a nutshell, mainline does not want platform specific code, but we
haven't figured out how to calculate static power without platform
specific code.

Cheers,
Javi