Re: [PATCH 1/3] dt-bindings: hwmon: Add maxim max31790 driver bindings

[Chanh Nguyen]

On 18/03/2024 17:00, Krzysztof Kozlowski wrote:
> On 18/03/2024 10:51, Chanh Nguyen wrote:
> > > It does not look like you tested the bindings, at least after quick
> > > look. Please run `make dt_binding_check` (see
> > > Documentation/devicetree/bindings/writing-schema.rst for instructions).
> > > Maybe you need to update your dtschema and yamllint.
> >
> >
> > I tested the binding, I didn't see any warning/error log. Please review
> > my logs as below
>
> Hm, I don't remember what brought my attention to possible error. Maybe
> I mistyped my template.
>
> > => make dt_binding_check DT_SCHEMA_FILES=/hwmon/max31790.yaml
> > make[1]: Entering directory '/DISK4T/work/community/linux/out'
> >     DTEX    Documentation/devicetree/bindings/hwmon/max31790.example.dts
> >     DTC_CHK Documentation/devicetree/bindings/hwmon/max31790.example.dtb
> > make[1]: Leaving directory '/DISK4T/work/community/linux/out'
> >
> > > > Signed-off-by: Chanh Nguyen <chanh@xxxxxxxxxxxxxxxxxxxxxx>
> > > > ---
> > > >    .../devicetree/bindings/hwmon/max31790.yaml   | 44 +++++++++++++++++++
> > > >    1 file changed, 44 insertions(+)
> > > >    create mode 100644 Documentation/devicetree/bindings/hwmon/max31790.yaml
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/hwmon/max31790.yaml b/Documentation/devicetree/bindings/hwmon/max31790.yaml
> > > > new file mode 100644
> > > > index 000000000000..5a93e6bdebda
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/hwmon/max31790.yaml
> > >
> > > Filename like compatible.
> >
> > Yes, I'll update that in v2
> >
> > > > @@ -0,0 +1,44 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/hwmon/max31790.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: The Maxim MAX31790 Fan Controller
> > > > +
> > > > +maintainers:
> > > > +  - Jean Delvare <jdelvare@xxxxxxxx>
> > > > +  - Guenter Roeck <linux@xxxxxxxxxxxx>
> > >
> > > You should have here someone responsible for hardware, not subsystem
> > > maintainers.
> >
> > Hi Krzysztof,
> > I checked the history of the drivers/hwmon/max31790.c and see Guenter
> > Roeck <linux@xxxxxxxxxxxx> as an important maintainer. I saw many
> > commits from him. So, I add him to maintainer list.
>
> OK
>
> > > > +
> > > > +description: >
> > > > +  The MAX31790 controls the speeds of up to six fans using six
> > > > +  independent PWM outputs. The desired fan speeds (or PWM duty cycles)
> > > > +  are written through the I2C interface.
> > > > +
> > > > +  Datasheets:
> > > > +    https://datasheets.maximintegrated.com/en/ds/MAX31790.pdf
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    const: maxim,max31790
> > > > +
> > > > +  reg:
> > > > +    maxItems: 1
> > >
> > > That's weirdly empty.
> >
> > Hi Krzysztof,
> > I have not yet understood your comment here. Please help give more
> > details for my missing! Thank Krzysztof!
>
> I expect many more properties of a fan controller. Resources (clocks,
> PWMs, supplies) and FAN specific properties.

Hi Krzysztof,

I'm creating a base binding document for the max31790 driver. I'm basing 
it on the drivers/hwmon/max31790.c. Currently, the max31790.c driver has 
not yet implemented other properties, such as clocks, fan-supply, pwms, 
etc. So I just introduced the "compatible" and "reg" properties.

In the near future, if any other properties are necessary, I think we 
will implement them in drivers/hwmon/max31790.c then update this binding 
document.

I look at other binding documents, I also see something similar. They 
just introduce the "compatible" and "reg" properties.

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/hwmon/adi,max31760.yaml 


https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/hwmon/adt7475.yaml

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/hwmon/adi,ad741x.yaml

This is only my view. It's a pleasure to hear your advice. Thanks!


> > > > +
> > > > +required:
> > > > +  - compatible
> > > > +  - reg
> > > > +
> > >
> > > You miss allOf: with $ref to fan controller schema.
> >
> > Thank Krzysztof,
> > I'll add the allOf at v2.
> >
> > > > +additionalProperties: false
> > > > +
> > > > +examples:
> > > > +  - |
> > > > +    i2c {
> > > > +      #address-cells = <1>;
> > > > +      #size-cells = <0>;
> > > > +
> > > > +      max31790@20 {
> > >
> > > Node names should be generic. See also an explanation and list of
> > > examples (not exhaustive) in DT specification:
> > > https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
> >
> > I suggest some node names, such as "i2c-fan" or "fan-controller" . Can
> > you please share your ideas with me!
>
> Look at recent commits and patches for similar type of a device.

Hi Krzysztof,

I checked on recent commits and found something of a similar type.

adi,max31760.yaml
        fan-controller@50 {
            reg = <0x50>;
            compatible = "adi,max31760";
        };

hpe,gxp-fan-ctrl.yaml
    fan-controller@1000c00 {
      compatible = "hpe,gxp-fan-ctrl";
      reg = <0x1000c00 0x200>, <0xd1000000 0xff>, <0x80200000 0x100000>;
      reg-names = "base", "pl", "fn2";
    };


adi,axi-fan-control.yaml
        axi_fan_control: axi-fan-control@80000000 {
            compatible = "adi,axi-fan-control-1.00.a";
            reg = <0x0 0x80000000 0x10000>;
            clocks = <&clk 71>;
            interrupts = <0 110 0>;
            pulses-per-revolution = <2>;
        };

I think "fan-controller" is a good node name. Do you think so?

> Best regards,
> Krzysztof