Re: [PATCH 0/3] drivers: Frequency constraint infrastructure

[Rafael J. Wysocki]

On Fri, Jan 11, 2019 at 10:18 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
>
> Hi,
>
> This commit introduces the frequency constraint infrastructure, which
> provides a generic interface for parts of the kernel to constraint the
> working frequency range of a device.
>
> The primary users of this are the cpufreq and devfreq frameworks. The
> cpufreq framework already implements such constraints with help of
> notifier chains (for thermal and other constraints) and some local code
> (for user-space constraints). The devfreq framework developers have also
> shown interest [1] in such a framework, which may use it at a later
> point of time.
>
> The idea here is to provide a generic interface and get rid of the
> notifier based mechanism.
>
> Only one constraint is added for now for the cpufreq framework and the
> rest will follow after this stuff is merged.
>
> Matthias Kaehlcke was involved in the preparation of the first draft of
> this work and so I have added him as Co-author to the first patch.
> Thanks Matthias.
>
> FWIW, This doesn't have anything to do with the boot-constraints
> framework [2] I was trying to upstream earlier :)

This is quite a bit of code to review, so it will take some time.

One immediate observation is that it seems to do quite a bit of what
is done in the PM QoS framework, so maybe there is an opportunity for
some consolidation in there.

Cheers,
Rafael