Re: [PATCH] dt-bindings: hwmon: microchip,emc2305: add vcc-supply and #cooling-cells

[Conor Dooley <conor@kernel.org>]

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On Mon, Aug 24, 2026 at 05:42:59PM +0200, Vincent Jardin via B4 Relay wrote:
> From: Vincent Jardin <vjardin@free.fr>
> 
> Both properties are missing, so a board that supplies either fails with
> dtbs_check:
> 
>   fan-controller@2c (microchip,emc2305): '#cooling-cells', 'vcc-supply'
>   do not match any of the regexes: '^fan@[0-4]$', '^pinctrl-[0-9]+$'
> 
> The #cooling-cells property belongs to the controller node, which is
> where the driver actually registers.
> 
> Two cells is what that registration needs: a cooling-maps entry
> references the fan as <&emc2305 min max>.
> 
> Two cells also documents what the driver supports today. The
> pwm-separate path registers one cooling device per PWM against the same
> node, and they all get cdev_id 0, so no cell count can tell them apart.
> That is a driver issue, noted here but not addressed.
> 
> The examples in this binding put that property on the fan@N subnodes
> instead, which does not match what the driver does: they are left alone
> here rather than changed blind.

That seems correct though and putting it in the device node when there's 4
fans that could interact with different zones seems wrong. Shouldn't the
driver be fixed instead?

> vcc-supply describes the chip's own rail, which matters on boards where
> the sensor sits behind a switched supply.
> 
> Signed-off-by: Vincent Jardin <vjardin@free.fr>
> ---
>  Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml b/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> index 8c2548539d7fd..47640214de100 100644
> --- a/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> +++ b/Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
> @@ -44,6 +44,11 @@ properties:
>             - 0 (Open-Drain)
>             - 1 (Push-Pull)
>  
> +  vcc-supply: true
> +
> +  "#cooling-cells":
> +    const: 2
> +
>  patternProperties:
>    '^fan@[0-4]$':
>      $ref: fan-common.yaml#
> 
> ---
> base-commit: 0a0d1d55dad570724bf8c7ea83409639cfb4be9b
> change-id: 20260824-for-upstream-dt-emc2305-vcc-cooling-251655c99ef8
> 
> Best regards,
> -- 
> Vincent Jardin <vjardin@free.fr>
> 
> 

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