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

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Message-ID: <YAG/pNXQOS+C2zLr@builder.lan>
Date:   Fri, 15 Jan 2021 10:15:32 -0600
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Roja Rani Yarubandi <rojay@...eaurora.org>
Cc:     ulf.hansson@...aro.org, robh+dt@...nel.org, wsa@...nel.org,
        swboyd@...omium.org, dianders@...omium.org,
        saiprakash.ranjan@...eaurora.org, mka@...omium.org,
        akashast@...eaurora.org, msavaliy@....qualcomm.com,
        parashar@...eaurora.org, rnayak@...eaurora.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        agross@...nel.org, linux-i2c@...r.kernel.org
Subject: Re: [PATCH 1/3] dt-bindings: power: Introduce
 'assigned-performance-states' property

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@...eaurora.org>
> ---
>  .../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@...40000 {
> +        compatible = "foo,power-controller";
> +        reg = <0x12340000 0x1000>;
> +        #power-domain-cells = <0>;
> +    };
> +
> +    parent5: power-controller@...10000 {
> +        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@...41000 {
> +        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>:

Regards,
Bjorn

> +    };
> -- 
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member 
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>