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

[Krzysztof Kozlowski <krzk@kernel.org>]

On Tue, Nov 03, 2026 at 10:43:57PM +0100, 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.
> 
> 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(-)

drivers/thermal/thermal_of.c still uses u32. Maybe we should have
of_property_read_s32_array() wrapper so the binding can match the ABI
code exactly?

Rob?

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>

Best regards,
Krzysztof