Re: [PATCH v2 1/2] dt-bindings: thermal: imx: Document calibration offset property

[Frank Li <Frank.li@oss.nxp.com>]

On Thu, Jul 09, 2026 at 04:10:21PM +0800, HaoNing Cheng via B4 Relay wrote:
> [You don't often get email from devnull+haoning.cheng.cn.bosch.com@kernel.org. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> From: HaoNing Cheng <Haoning.CHENG@cn.bosch.com>
>
> Some boards need a small per-design correction to align the reported CPU
> temperature with board-level measurements.
>
> Document the optional fsl,temp-calibration-offset-millicelsius property,
> a signed offset in millicelsius that is added to the calculated sensor
> temperature.

why board difference cause such offset, I suppose it is cause by SoC
variance. The offset may difference if you change to another chip. another
words, if you have 1000 boards, Is this offset the same?


> The property is optional and the existing behaviour is kept
> when it is omitted.
>
> Update the binding example to show its usage.
>
> Signed-off-by: HaoNing Cheng <Haoning.CHENG@cn.bosch.com>
> ---
>  Documentation/devicetree/bindings/thermal/imx-thermal.yaml | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/thermal/imx-thermal.yaml b/Documentation/devicetree/bindings/thermal/imx-thermal.yaml
> index 949b154856c5..eb7243a7ebaf 100644
> --- a/Documentation/devicetree/bindings/thermal/imx-thermal.yaml
> +++ b/Documentation/devicetree/bindings/thermal/imx-thermal.yaml
> @@ -59,6 +59,13 @@ properties:
>    clocks:
>      maxItems: 1
>
> +  fsl,temp-calibration-offset-millicelsius:
> +    maxItems: 1

suppose it int32, why need maxItems here?

Frank

> +    description:
> +      A signed calibration offset, in millicelsius, added to the calculated
> +      sensor temperature to compensate for board-level measurement
> +      differences. When absent, no offset is applied.
> +
>    "#thermal-sensor-cells":
>      const: 0
>
> @@ -109,6 +116,7 @@ examples:
>              nvmem-cells = <&tempmon_calib>, <&tempmon_temp_grade>;
>              nvmem-cell-names = "calib", "temp_grade";
>              clocks = <&clks IMX6SX_CLK_PLL3_USB_OTG>;
> +            fsl,temp-calibration-offset-millicelsius = <(-6400)>;
>              #thermal-sensor-cells = <0>;
>          };
>      };
>
> --
> 2.43.0
>
>
>