Re: [PATCH v2 1/2] dt-bindings: devfreq: Document support for Airoha Subsystem Scale

[Conor Dooley <conor@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 4834 bytes --]

On Fri, Oct 09, 2026 at 09:33:28AM +0200, Christian Marangi wrote:
> Airoha SoC contains multiple subsystems that are scaled to a
> specific OPP taking the CPU clock as reference. Such subsystem
> can enter idle or performance state based on the system load
> and power consumption conditions.
> 
> Example of such subsystems are GSW (Gigabit Switch), NPU (Custom
> Risc Co-Processor for Network acceleration), SOE (Crypto Module) BUS...

The device you document here does not appear to exist at all, since it
just consumes a clock without any registers or anything. Why can't these
operating points be added to the actual consumers: the switch, the npu,
or event the bus itself in one case. In the bus case, I think that's
exactly what simple-pm-bus does?

Confused,
Conor.

> 
> Document all the required property and provide examples for the various
> subsystem OPP + subsystem scale nodes.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> ---
>  .../devfreq/airoha,subsystem-scale.yaml       | 114 ++++++++++++++++++
>  1 file changed, 114 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/devfreq/airoha,subsystem-scale.yaml
> 
> diff --git a/Documentation/devicetree/bindings/devfreq/airoha,subsystem-scale.yaml b/Documentation/devicetree/bindings/devfreq/airoha,subsystem-scale.yaml
> new file mode 100644
> index 000000000000..2cf7f23a926c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/devfreq/airoha,subsystem-scale.yaml
> @@ -0,0 +1,114 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/devfreq/airoha,subsystem-scale.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Airoha SoC Subsystem Scale Driver
> +
> +maintainers:
> +  - Christian Marangi <ansuelsmth@gmail.com>
> +
> +description:
> +  Airoha SoC contains multiple subsystems that are scaled to a
> +  specific OPP taking the CPU clock as reference. Such subsystem
> +  can enter idle or performance state based on the system load
> +  and power consumption conditions.
> +
> +  Example of such subsystems are GSW (Gigabit Switch), NPU (Custom
> +  Risc Co-Processor for Network acceleration), SOE (Crypto Module) BUS...
> +
> +properties:
> +  compatible:
> +    const: airoha,an7581-subsystem-scale
> +
> +  clocks:
> +    maxItems: 1
> +
> +  operating-points-v2:
> +    description:
> +      OPP table of the related subsystem supported rates that referenced
> +      clocks will be scaled to.
> +
> +required:
> +  - compatible
> +  - clocks
> +  - operating-points-v2
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/en7523-clk.h>
> +
> +    npu_opp_table: opp-table-npu {
> +        compatible = "operating-points-v2";
> +
> +        npu_low: opp-400000000 {
> +           opp-hz = /bits/ 64 <400000000>;
> +        };
> +
> +        npu_high: opp-720000000 {
> +           opp-hz = /bits/ 64 <720000000>;
> +        };
> +    };
> +
> +    emi_opp_table: opp-table-emi {
> +        compatible = "operating-points-v2";
> +
> +        emi_low: opp-400000000 {
> +            opp-hz = /bits/ 64 <400000000>;
> +        };
> +
> +        emi_high: opp-540000000 {
> +           opp-hz = /bits/ 64 <540000000>;
> +        };
> +    };
> +
> +    bus_opp_table: opp-table-bus {
> +        compatible = "operating-points-v2";
> +
> +        bus_low: opp-200000000 {
> +           opp-hz = /bits/ 64 <200000000>;
> +        };
> +
> +        bus_high: opp-300000000 {
> +           opp-hz = /bits/ 64 <300000000>;
> +        };
> +    };
> +
> +    gsw_opp_table: opp-table-gsw {
> +        compatible = "operating-points-v2";
> +
> +        gsw_low: opp-200000000 {
> +            opp-hz = /bits/ 64 <200000000>;
> +        };
> +
> +        gsw_high: opp-500000000 {
> +           opp-hz = /bits/ 64 <500000000>;
> +        };
> +    };
> +
> +    npu-subsystem {
> +        compatible = "airoha,an7581-subsystem-scale";
> +        operating-points-v2 = <&npu_opp_table>;
> +        clocks = <&scuclk EN7523_CLK_NPU>;
> +    };
> +
> +    emi-subsystem {
> +        compatible = "airoha,an7581-subsystem-scale";
> +        operating-points-v2 = <&emi_opp_table>;
> +        clocks = <&scuclk EN7523_CLK_EMI>;
> +    };
> +
> +    bus-subsystem {
> +        compatible = "airoha,an7581-subsystem-scale";
> +        operating-points-v2 = <&bus_opp_table>;
> +        clocks = <&scuclk EN7523_CLK_BUS>;
> +    };
> +
> +    gsw-subsystem {
> +        compatible = "airoha,an7581-subsystem-scale";
> +        operating-points-v2 = <&gsw_opp_table>;
> +        clocks = <&scuclk EN7523_CLK_GSW>;
> +    };
> -- 
> 2.55.0
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]