linux-kernel - RE: [PATCH 05/11] PM / devfreq: governors: Return device frequency limits instead of user limits

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Date:   Mon, 28 May 2018 14:04:44 +0900
From:   MyungJoo Ham <myungjoo.ham@...sung.com>
To:     undisclosed-recipients:;
CC:     Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Brian Norris <briannorris@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>
Subject: RE: [PATCH 05/11] PM / devfreq: governors: Return device frequency
 limits instead of user limits

>The performance, powersave and simpleondemand governors can return
>df->min/max_freq, which are the user defined frequency limits.
>update_devfreq() already takes care of adjusting the target frequency
>with the user limits if necessary, therefore we can return
>df->scaling_min/max_freq instead, which is the min/max frequency
>supported by the device at a given time (depending on the
>enabled/disabled OPPs)
>
>Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
>---
> drivers/devfreq/governor_performance.c    | 2 +-
> drivers/devfreq/governor_powersave.c      | 2 +-
> drivers/devfreq/governor_simpleondemand.c | 6 +++---
> 3 files changed, 5 insertions(+), 5 deletions(-)
>

Actually, even scaling_max_freq and scaling_min_freq are
covered centerally at devfreq.c:update_devfreq();

Wouldn't it be sufficient to return UINT_MAX for performance
and return UINT_MIN (0) for powersave, if the purpose is to
remove redundancy?

In the same sense, we may return UINT_MAX for freq-increasing
case for simpleondemand as well, because they are filtered
centrally anyway.

(This commit might be better merged to 4/11 in that case as well.)


Cheers,
MyungJoo