Re: [PATCH v2 2/2] dt-bindings: hwmon: pmbus: mps,mpq8785: add #thermal-sensor-cells

[Conor Dooley <conor@kernel.org>]

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On Thu, Oct 01, 2026 at 09:28:23AM +0200, Vincent Jardin via B4 Relay wrote:
> From: Vincent Jardin <vjardin@free.fr>
> 
> Since commit
>   3aa74796cfd0 ("hwmon: (pmbus) Register with thermal for PSC_TEMPERATURE")
> the PMBus core calls devm_thermal_of_zone_register() for every
> temperature input, so the devices of this binding can be referenced as
> thermal sensors.

Commit messages for bindings should reference hardware in their
justification, not what a particular OS has decided to do.

> By code review, it should work for the MPQ and MPM device bindings.
> They register a single page with PMBUS_HAVE_TEMP through
> pmbus_do_probe(), it means that one device has one
> temperature input, temp1.
> 
> The PMBus core registers the first temperature input as sensor 0, so no
> cell is needed.

I don't understand this, if it has multiple sensors, each could be
referenced by something and it would need cells. It only has single
input, then that's the justification that needs to be provided here.
What software does, especially in generic code, should not be used to
justify a binding change.

I checked the devices supported by the mpq8785 driver and none of them
actually appear to have temperature inputs at all?

Confused,
Conor.

> 
> Signed-off-by: Vincent Jardin <vjardin@free.fr>
> ---
>  Documentation/devicetree/bindings/hwmon/pmbus/mps,mpq8785.yaml | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/pmbus/mps,mpq8785.yaml b/Documentation/devicetree/bindings/hwmon/pmbus/mps,mpq8785.yaml
> index d7a32fb3b7af..6257a8030e53 100644
> --- a/Documentation/devicetree/bindings/hwmon/pmbus/mps,mpq8785.yaml
> +++ b/Documentation/devicetree/bindings/hwmon/pmbus/mps,mpq8785.yaml
> @@ -34,6 +34,9 @@ properties:
>      maximum: 4095
>      default: 706
>  
> +  "#thermal-sensor-cells":
> +    const: 0
> +
>  required:
>    - compatible
>    - reg
> 
> -- 
> 2.43.0
> 
> 

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