Re: [PATCH v4 1/2] dt-bindings: thermal: imx: Document calibration offset property

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

On Fri, Jul 10, 2026 at 11:03:36AM +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.

Thanks you for patch, but you have not answer my previous question yet.

"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?"

Or did you tune this value for each boards?

Frank

>
> Document the optional fsl,temp-calibration-offset-millicelsius property,
> a signed offset in millicelsius that is added to the calculated sensor
> temperature. 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 | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/thermal/imx-thermal.yaml b/Documentation/devicetree/bindings/thermal/imx-thermal.yaml
> index 949b154856c5..b9afffd98f84 100644
> --- a/Documentation/devicetree/bindings/thermal/imx-thermal.yaml
> +++ b/Documentation/devicetree/bindings/thermal/imx-thermal.yaml
> @@ -59,6 +59,14 @@ properties:
>    clocks:
>      maxItems: 1
>
> +  fsl,temp-calibration-offset-millicelsius:
> +    minimum: -28580
> +    maximum: 28580
> +    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 +117,7 @@ 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
>
>
>