linux-kernel - Re: [PATCH v2] cpufreq: Avoid configuring old governors as default with intel

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Date:   Tue, 27 Oct 2020 08:31:30 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Julia Lawall <julia.lawall@...ia.fr>,
        Mel Gorman <mgorman@...e.de>, Ingo Molnar <mingo@...hat.com>,
        kernel-janitors@...r.kernel.org,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        linux-kernel@...r.kernel.org,
        Valentin Schneider <valentin.schneider@....com>,
        Gilles Muller <Gilles.Muller@...ia.fr>,
        srinivas.pandruvada@...ux.intel.com,
        Linux PM <linux-pm@...r.kernel.org>,
        Len Brown <len.brown@...el.com>
Subject: Re: [PATCH v2] cpufreq: Avoid configuring old governors as default
 with intel_pstate

On 23-10-20, 17:15, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Commit 33aa46f252c7 ("cpufreq: intel_pstate: Use passive mode by
> default without HWP") was meant to cause intel_pstate to be used
> in the passive mode with the schedutil governor on top of it, but
> it missed the case in which either "ondemand" or "conservative"
> was selected as the default governor in the existing kernel config,
> in which case the previous old governor configuration would be used,
> causing the default legacy governor to be used on top of intel_pstate
> instead of schedutil.
> 
> Address this by preventing "ondemand" and "conservative" from being
> configured as the default cpufreq governor in the case when schedutil
> is the default choice for the default governor setting.
> 
> [Note that the default cpufreq governor can still be set via the
>  kernel command line if need be and that choice is not limited,
>  so if anyone really wants to use one of the legacy governors by
>  default, it can be achieved this way.]
> 
> Fixes: 33aa46f252c7 ("cpufreq: intel_pstate: Use passive mode by default without HWP")
> Reported-by: Julia Lawall <julia.lawall@...ia.fr>
> Cc: 5.8+ <stable@...r.kernel.org> # 5.8+
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> 
> The v2 addresses a review comment from Viresh regarding of the expression format
> and adds a missing Reported-by for Julia.
> 
> ---
>  drivers/cpufreq/Kconfig |    2 ++
>  1 file changed, 2 insertions(+)

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh