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

[Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>]

Hi Lukasz,

On 11/5/26 11:45, Lukasz Luba wrote:
> 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>
Thanks for the review