linux-kernel - Re: [PATCH 2/3] dt-bindings: hwmon: Add Microchip EMC2101 support

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Message-ID: <CAKR-sGf01xtOF9dY9yb2i67PV5FHHe3GGKk7ingjTOOfqWA5FA@mail.gmail.com>
Date: Sat, 28 Jun 2025 10:43:05 +0200
From: Álvaro Fernández Rojas <noltari@...il.com>
To: Rob Herring <robh@...nel.org>
Cc: jdelvare@...e.com, linux@...ck-us.net, krzk+dt@...nel.org, 
	conor+dt@...nel.org, corbet@....net, linux-hwmon@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-doc@...r.kernel.org
Subject: Re: [PATCH 2/3] dt-bindings: hwmon: Add Microchip EMC2101 support

Hi Rob,

El vie, 27 jun 2025 a las 23:34, Rob Herring (<robh@...nel.org>) escribió:
>
> On Thu, Jun 26, 2025 at 01:33:50PM +0200, Álvaro Fernández Rojas wrote:
> > Introduce yaml schema for Microchip emc2101 pwm fan controller with
> > temperature monitoring.
> >
> > Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
> > ---
> >  .../bindings/hwmon/microchip,emc2101.yaml     | 52 +++++++++++++++++++
> >  1 file changed, 52 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/hwmon/microchip,emc2101.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/hwmon/microchip,emc2101.yaml b/Documentation/devicetree/bindings/hwmon/microchip,emc2101.yaml
> > new file mode 100644
> > index 000000000000..e73f1f9d43f4
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/hwmon/microchip,emc2101.yaml
> > @@ -0,0 +1,52 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/hwmon/microchip,emc2101.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Microchip EMC2101 SMBus compliant PWM fan controller
> > +
> > +maintainers:
> > +  - Álvaro Fernández Rojas <noltari@...il.com>
> > +
> > +description:
> > +  Microchip EMC2101 pwm controller which supports up to 1 fan, 1 internal
> > +  temperature sensor, 1 external temperature sensor and an 8 entry look
> > +  up table to create a programmable temperature response.
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - microchip,emc2101
> > +      - microchip,emc2101-r
> > +
> > +  reg:
> > +    maxItems: 1
> > +
>
> > +  '#address-cells':
> > +    const: 1
> > +
> > +  '#size-cells':
> > +    const: 0
>
> What are these for? You don't have any child nodes.

EMC2101 can control a single fan, so I guess I should add the following here:

  '#pwm-cells':
    const: 2
    description: |
      Number of cells in a PWM specifier.
      - cell 0: The PWM frequency
      - cell 1: The PWM polarity: 0 or PWM_POLARITY_INVERTED

patternProperties:
  '^fan@0$':
    $ref: fan-common.yaml#
    unevaluatedProperties: false
    properties:
      reg:
        description:
          The fan number used to determine the associated PWM channel.
        maxItems: 1

    required:
      - reg

>
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    i2c {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        fan_controller: fan-controller@4c {
> > +            compatible = "microchip,emc2101";
> > +            reg = <0x4c>;
> > +
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;

And the following here:

            #pwm-cells = <2>;

            fan@0 {
                reg = <0x0>;
                pwms = <&fan_controller 5806 0>;
                #cooling-cells = <2>;
            };

Would that fix the issue?

> > +        };
> > +    };
> > +...
> > --
> > 2.39.5
> >

Best regards,
Álvaro.