linux-kernel - Re: [PATCH 1/6] dt-bindings: clock: qcom,dispcc-sm8x50: add mmcx power domain

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Date:   Thu, 1 Jul 2021 18:58:22 +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: [PATCH 1/6] dt-bindings: clock: qcom,dispcc-sm8x50: add mmcx
 power domain

On Thu, 1 Jul 2021 at 18:39, Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On Thu, 1 Jul 2021 at 19:17, Ulf Hansson <ulf.hansson@...aro.org> wrote:
> >
> > On Wed, 30 Jun 2021 at 15:31, Dmitry Baryshkov
> > <dmitry.baryshkov@...aro.org> wrote:
> > >
> > > On sm8250 dispcc requires MMCX power domain to be powered up before
> > > clock controller's registers become available. For now sm8250 was using
> > > external regulator driven by the power domain to describe this
> > > relationship. Switch into specifying power-domain and required opp-state
> > > directly.
> > >
> > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > > ---
> > >  .../bindings/clock/qcom,dispcc-sm8x50.yaml    | 19 +++++++++++++++++++
> > >  1 file changed, 19 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/clock/qcom,dispcc-sm8x50.yaml b/Documentation/devicetree/bindings/clock/qcom,dispcc-sm8x50.yaml
> > > index 0cdf53f41f84..48d86fb34fa7 100644
> > > --- a/Documentation/devicetree/bindings/clock/qcom,dispcc-sm8x50.yaml
> > > +++ b/Documentation/devicetree/bindings/clock/qcom,dispcc-sm8x50.yaml
> > > @@ -55,6 +55,16 @@ properties:
> > >    reg:
> > >      maxItems: 1
> > >
> > > +  power-domains:
> > > +    description:
> > > +      A phandle and PM domain specifier for the MMCX power domain.
> > > +    maxItems: 1
> > > +
> >
> > Should you perhaps state that this is a parent domain? Or it isn't?
> >
> > Related to this and because this is a power domain provider, you
> > should probably reference the common power-domain bindings somewhere
> > here. Along the lines of this:
> >
> > - $ref: power-domain.yaml#
> >
> > As an example, you could have a look at
> > Documentation/devicetree/bindings/power/pd-samsung.yaml.
>
> I'll take a look.
>
> >
> > > +  required-opps:
> > > +    description:
> > > +      Performance state to use for MMCX to enable register access.
> > > +    maxItems: 1
> >
> > According to the previous discussions, I was under the assumption that
> > this property belongs to a consumer node rather than in the provider
> > node, no?
>
> It is both a consumer and a provider. It consumes SM8250_MMCX from
> rpmhpd and provides MMSC_GDSC.

That sounds a bit weird to me.

In my view and per the common power domain bindings (as pointed to
above): If a power domain provider is a consumer of another power
domain, that per definition means that there is a parent domain
specified.

[...]

Kind regards
Uffe