Re: [PATCH] dt-bindings: thermal: Use signed integers for coefficients

[Lukasz Luba <lukasz.luba@arm.com>]

Hi Daniel,

On 11/3/26 21:43, Daniel Lezcano wrote:
> The coefficients property describes the coefficients of a linear
> equation used to derive a thermal zone temperature. Both the slope
> and the constant offset can be negative, and the thermal core stores
> them as signed integers.
> 
> Existing Device Trees already rely on signed values. OMAP4460 uses
> an offset of -9301, while OMAP5 uses offsets of -1791 and -2992.
> Broadcom platforms also use negative slopes. Declaring the property
> as uint32-array does not represent these values correctly.

This looks like a good argument which was missed back then (that
the negative values are possible).

> 
> Change the property type to int32-array so schema validation decodes
> the cells as signed 32-bit integers, matching their intended meaning
> and the thermal implementation. The cell width and binary encoding
> remain unchanged, preserving compatibility with existing Device
> Trees.
> 
> Fixes: 1202a442a31f ("dt-bindings: thermal: Add yaml bindings for thermal zones")
> Signed-off-by: Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>
> ---
>   Documentation/devicetree/bindings/thermal/thermal-zones.yaml | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
> index 999ad40a20d5..72e419124f98 100644
> --- a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
> +++ b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
> @@ -101,7 +101,7 @@ patternProperties:
>             thermal zone.
>   
>         coefficients:
> -        $ref: /schemas/types.yaml#/definitions/uint32-array
> +        $ref: /schemas/types.yaml#/definitions/int32-array
>           description:
>             An array of integers containing the coefficients of a linear equation
>             that binds all the sensors listed in this thermal zone.

Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

Regards,
Lukasz