linux-kernel - Re: [PATCH v2 1/3] dt-bindings: hwmon: fan: Add fan binding to schema

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Date:   Tue, 11 Oct 2022 12:24:57 -0400
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Naresh Solanki <naresh.solanki@...ements.com>,
        devicetree@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>
Subject: Re: [PATCH v2 1/3] dt-bindings: hwmon: fan: Add fan binding to schema

On 11/10/2022 06:47, Naresh Solanki wrote:
> Add common fan properties bindings to a schema.
> 
> Bindings for fan controllers can reference the common schema for the
> fan
> 
> child nodes:
> 
>   patternProperties:
>     "^fan@[0-2]":
>       type: object
>       allOf:
>         - $ref: fan-common.yaml#
> 
> Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
> ---
>  .../devicetree/bindings/hwmon/fan-common.yaml | 80 +++++++++++++++++++
>  1 file changed, 80 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/fan-common.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/fan-common.yaml b/Documentation/devicetree/bindings/hwmon/fan-common.yaml
> new file mode 100644
> index 000000000000..abc8375da646
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/fan-common.yaml
> @@ -0,0 +1,80 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwmon/fan-common.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Common fan properties

Is a fan a hardware monitoring device? Maybe this should not be called a
fan?

> +
> +maintainers:
> +  - Naresh Solanki <naresh.solanki@...ements.com>
> +
> +properties:
> +  max-rpm:
> +    description:
> +      Max RPM supported by fan
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +  pulse-per-revolution:
> +    description:
> +      The number of pulse from fan sensor per revolution.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +  target-rpm:
> +    description:
> +      Target RPM the fan should be configured during driver probe.

I think target depends on conditions, e.g. it is rarely one target.

> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +  pwm-frequency:
> +    description:
> +      PWM frequency for fan.
> +    $ref: /schemas/types.yaml#/definitions/uint32

Use common units, so -hz

However I wonder if frequency is appropriate here - I thought PWMs are
rather configured via duty cycles.

> +
> +  pwm-polarity-inverse:
> +    description:
> +      PWM polarity for fan.

Rather: Inversed PWM polarity for the fan.

> +    type: boolean
> +
> +  label:
> +    description:
> +      Optional fan label
> +    $ref: /schemas/types.yaml#/definitions/string

Ref is not needed, core brings it.

> +
> +additionalProperties: true
> +
> +examples:
> +  - |
> +
> +

Drop unneeded empty lines.

> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        fan-controller@30 {
> +            compatible = "maxim,max6639";
> +            reg = <0x30>;
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            fan@0 {
> +                reg = <0>;
> +                label = "CPU0_Fan";
> +                max-rpm = <32000>;
> +                pulse-per-revolution = <2>;
> +                target-rpm = <2000>;
> +                pwm-frequency = <25000>;
> +            };
> +
> +            fan@1 {
> +                reg = <1>;
> +                label = "PCIe0_Fan";
> +                max-rpm = <32000>;
> +                pulse-per-revolution = <2>;
> +                target-rpm = <2000>;
> +                pwm-frequency = <25000>;
> +            };
> +

Drop unneeded empty lines.

> +        };
> +    };
> +
> +...
> 
> base-commit: 0cf46a653bdae56683fece68dc50340f7520e6c4

Best regards,
Krzysztof