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

[Rajendra Nayak]

On 8/5/2020 12:09 PM, Stephen Boyd wrote:
> Quoting Rajendra Nayak (2020-08-04 04:46:54)
> > 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 of a fixed clock and not support
>
> s/of/off/
>
> > dyamically scaling the device's performance, also known as DVFS techniques.
>
> s/dyamically/dynamically/
>
> > Add a property 'assigned-performance-states' which client devices can
> > use to set this default performance state on their power-domains.
> >
> > Signed-off-by: Rajendra Nayak <rnayak@xxxxxxxxxxxxxx>
> > ---
> >   .../devicetree/bindings/power/power-domain.yaml    | 47 ++++++++++++++++++++++
> >   1 file changed, 47 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/power/power-domain.yaml b/Documentation/devicetree/bindings/power/power-domain.yaml
> > index ff5936e..48e9319 100644
> > --- a/Documentation/devicetree/bindings/power/power-domain.yaml
> > +++ b/Documentation/devicetree/bindings/power/power-domain.yaml
> > @@ -66,6 +66,16 @@ 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 of a fixed clock and not support dyamically scaling the
>
> Same of and dynamically comment.
>
> > +       device's performance, also known as DVFS techniques. The list of performance
> > +       state values should correspond to the list of power domains specified as part
> > +       of the power-domains property.
>
> This is different than assigned-clock-rates. I guess that's OK because
> we don't need to assign parents with more specifiers. Maybe it should be
> worded more strongly to clearly state that each cell corresponds to one
> power domain? And that it should match the opp-level inside any OPP
> table for the power domain?

Sure, I'll reword it to make it clear that we need the same number of cells
as power-domains, and as you pointed out below that 0 corresponds to not setting
anything.

For the matching of opp-level inside the OPP table of the power-domain, I don't
think from the power-domain bindings we limit providers with only OPP tables to
support performance states? It could be just a range that the provider manages
internally?

And thanks for catching all my typos :), I'll have them fixed when I re-spin.

> > +
> >   required:
> >     - "#power-domain-cells"
> >   
> > @@ -129,3 +139,40 @@ 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>;
>
> I guess <0> means don't set anything?

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