linux-kernel - Re: [PATCH v2 4/4] PM: domains: Drop/restore performance state votes for devices at system PM

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Date:   Tue, 8 Jun 2021 16:39:03 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Stephan Gerhold <stephan@...hold.net>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Dmitry Osipenko <digetx@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Roja Rani Yarubandi <rojay@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Rajendra Nayak <rnayak@...eaurora.org>
Subject: Re: [PATCH v2 4/4] PM: domains: Drop/restore performance state votes
 for devices at system PM

On Tue, 8 Jun 2021 at 16:20, Mark Brown <broonie@...nel.org> wrote:
>
> On Tue, Jun 08, 2021 at 04:08:55PM +0200, Ulf Hansson wrote:
>
> > Honestly, I am not sure about what the regulator-fixed-domain intends
> > to model, but I assume it's something that fits well to be modelled as
> > a plain regulator, to start with.
>
> > Perhaps Mark can chime in and spread some light over this?
>
> IIRC it's for situations where there's a device that's normally built as
> a separate chip that got built into a bigger SoC and wants to rear end
> something onto a power domain, I guess especially if the power domain
> doesn't cover the whole of a Linux device.

Alright, thanks for explaining!

Certainly something that should not be mixed up with a regular power
rail for shared resources (aka power-domain). Maybe it's worth trying
to extend the description in the DT binding a bit, so it doesn't get
abused?

Kind regards
Uffe