Re: [PATCH 1/3] dt-bindings: power: Introduce 'assigned-performance-states' property

[Rajendra Nayak]

On 1/15/2021 9:45 PM, Bjorn Andersson wrote:
> On Thu 24 Dec 05:12 CST 2020, Roja Rani Yarubandi wrote:
>
> > While most devices within power-domains which support performance states,
> > scale the performance state dynamically, some devices might want to
> > set a static/default performance state while the device is active.
> > These devices typically would also run off a fixed clock and not support
> > dynamically scaling the device's performance, also known as DVFS
> > techniques.
> >
> > Add a property 'assigned-performance-states' which client devices can
> > use to set this default performance state on their power-domains.
> >
> > Signed-off-by: Roja Rani Yarubandi <rojay@xxxxxxxxxxxxxx>
> > ---
> >   .../bindings/power/power-domain.yaml          | 49 +++++++++++++++++++
> >   1 file changed, 49 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/power/power-domain.yaml b/Documentation/devicetree/bindings/power/power-domain.yaml
> > index aed51e9dcb11..a42977a82d06 100644
> > --- a/Documentation/devicetree/bindings/power/power-domain.yaml
> > +++ b/Documentation/devicetree/bindings/power/power-domain.yaml
> > @@ -66,6 +66,18 @@ properties:
> >         by the given provider should be subdomains of the domain specified
> >         by this binding.
> >   
> > +  assigned-performance-states:
> > +    $ref: /schemas/types.yaml#/definitions/uint32-array
> > +    description:
> > +       Some devices might need to configure their power domains in a default
> > +       performance state while the device is active. These devices typcially
> > +       would also run off a fixed clock and not support dynamically scaling
> > +       the device's performance, also known as DVFS techniques. Each cell in
> > +       performance state value corresponds to one power domain specified as
> > +       part of the power-domains property. Performance state value can be an
> > +       opp-level inside an OPP table of the power-domain and need not match
> > +       with any OPP table performance state.
> > +
> >   required:
> >     - "#power-domain-cells"
> >   
> > @@ -131,3 +143,40 @@ examples:
> >               min-residency-us = <7000>;
> >           };
> >       };
> > +
> > +  - |
> > +    parent4: power-controller@12340000 {
> > +        compatible = "foo,power-controller";
> > +        reg = <0x12340000 0x1000>;
> > +        #power-domain-cells = <0>;
> > +    };
> > +
> > +    parent5: power-controller@43210000 {
> > +        compatible = "foo,power-controller";
> > +        reg = <0x43210000 0x1000>;
> > +        #power-domain-cells = <0>;
> > +        operating-points-v2 = <&power_opp_table>;
> > +
> > +        power_opp_table: opp-table {
> > +            compatible = "operating-points-v2";
> > +
> > +            power_opp_low: opp1 {
> > +                opp-level = <16>;
> > +            };
> > +
> > +            rpmpd_opp_ret: opp2 {
> > +                opp-level = <64>;
> > +            };
> > +
> > +            rpmpd_opp_svs: opp3 {
> > +                opp-level = <256>;
> > +            };
> > +        };
> > +    };
> > +
> > +    child4: consumer@12341000 {
> > +        compatible = "foo,consumer";
> > +        reg = <0x12341000 0x1000>;
> > +        power-domains = <&parent4>, <&parent5>;
> > +        assigned-performance-states = <0>, <256>;
>
> May I ask how this is different from saying something like:
>
> 	required-opps = <&??>, <&rpmpd_opp_svs>:

I think its potentially the same. We just don't have any code to handle this
binding in kernel yet (when this property is part of the device/consumer node)

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