linux-kernel - Re: [RESEND PATCH v2 3/7] PM: domains: Add support for runtime PM

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Message-ID: <CAPDyKFoeYOceAc-sfetJnEmL--rvO=rVQkCVxdYaZdnxOPwCJA@mail.gmail.com>
Date:   Fri, 9 Jul 2021 14:20:51 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Taniya Das <tdas@...eaurora.org>,
        Jonathan Marek <jonathan@...ek.ca>,
        Michael Turquette <mturquette@...libre.com>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        "Bryan O'Donoghue" <bryan.odonoghue@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v2 3/7] PM: domains: Add support for runtime PM

On Fri, 9 Jul 2021 at 13:39, Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> Hi,
>
> On Fri, 9 Jul 2021 at 11:25, Ulf Hansson <ulf.hansson@...aro.org> wrote:
> >
> > On Fri, 9 Jul 2021 at 06:32, Dmitry Baryshkov
> > <dmitry.baryshkov@...aro.org> wrote:
> > >
> > > Registers for some genpds can be located in the SoC area, powered up by
> > > another power domain. To enabled access to those registers, respective
> > > domain should be turned on.
> > >
> > > This patch adds basic infrastructure to the genpd code to allow
> > > implementing drivers for such genpd. PM domain can provide the parent
> > > device through the genpd->dev.parent pointer. If its provided at the
> > > pm_genpd_init() call time and if it is pm-enabled, genpd power_on and
> > > power_off operations will call pm_runtime_get_sync() before powering up
> > > the domain and pm_runtime_put_sync() after powering it down.
> > >
> > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> >
> > Hi Dmitry,
> >
> > Using runtime PM for the genpd provider device, is not the correct
> > approach. If the provider domain needs another domain to be powered on
> > to work correctly, that per definition means that it has a parent
> > domain.
> >
> > I suggest you try to build the correct PM domain topology, via using
> > pm_genpd_add_subdomain() or of_genpd_add_subdomain(), then genpd will
> > manages the power on/off for parent/child domain internally.
>
> Indeed, this patch seems redundant now, with the
> pm_genpd_add_subdomain call in place.
> Would you like me to resend a v3 just dropping this patch?

Yes, $subject patch isn't the way to go.

Let's continue discussing things on patch3/7 to conclude on the way forward.

[...]

Kind regards
Uffe