linux-kernel - Re: [RFC V2 1/6] cpufreq: Replace "max_transition_latency" with "dynamic

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Message-ID: <CAJZ5v0g-DgV6G-J9pkAYKooqgbJDV_ML8cR8wquKksN=x_JpoQ@mail.gmail.com>
Date:   Thu, 13 Jul 2017 18:19:53 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC V2 1/6] cpufreq: Replace "max_transition_latency" with "dynamic_switching"

On Thu, Jul 13, 2017 at 7:40 AM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> There is no limitation in the ondemand or conservative governors which
> disallow the transition_latency to be greater than 10 ms.
>
> The max_transition_latency field is rather used to disallow automatic
> dynamic frequency switching for platforms which didn't wanted these
> governors to run.
>
> Replace max_transition_latency with a boolean (dynamic_switching) and
> check for transition_latency == CPUFREQ_ETERNAL along with that. This
> makes it pretty straight forward to read/understand now.

Well, using CPUFREQ_ETERNAL for that on the driver side is still not
particularly straightforward IMO, so maybe add a
"no_dynamic_switching" to the driver structure and set it to "true"
for the one driver in question?

Thanks,
Rafael