[PATCH v7 0/2] thermal: imx: Add calibration offset support

[PATCH v7 0/2] thermal: imx: Add calibration offset support

[Haoning CHENG via B4 Relay]

Some i.MX boards need a small per-design correction to align the
reported CPU temperature with board-level measurements. This series
adds an optional DT property to specify such a calibration offset
and implements the corresponding support in the imx_thermal driver.

Patch 1 documents the new fsl,temp-calibration-offset-millicelsius
property in the i.MX thermal DT binding.

Patch 2 reads this property in the imx_thermal driver and applies
the offset to the i.MX6/6SX/7D calibration formulas. When the
property is absent, the default offset remains 0, preserving the
current behaviour.

Signed-off-by: Haoning CHENG <Haoning.CHENG@cn.bosch.com>
---
Changes in v7:
- Align the author name with the Signed-off-by trailer.
- Link to v6: https://patch.msgid.link/20260713-b4-symana21-11221-imx-thermal-support-upstream-6-18-v6-0-88a378faeca5@cn.bosch.com

Changes in v6:
- Align the author name with the Signed-off-by trailer.
- Link to v5: https://patch.msgid.link/20260713-b4-symana21-11221-imx-thermal-support-upstream-6-18-v5-0-69405c306c6b@cn.bosch.com

Changes in v5:
- Move calibration offset application out of c2 initialization, instead
  apply it in imx_get_temp(), imx_set_alarm_temp() and imx_set_panic_temp()
  for consistent style across i.MX6 and i.MX7D
- Subtract calibration offset from alarm_temp before the if-else block in
  imx_set_alarm_temp(), simplifying both SoC branches (Frank's suggestion)
- Link to v4: https://patch.msgid.link/20260710-b4-symana21-11221-imx-thermal-support-upstream-6-18-v4-0-1fef97d1c750@cn.bosch.com

Changes in v4:
- dt-bindings: drop maxItems to allow minimum/maximum constraints for
  temp-calibration-offset-millicelsius
- Link to v3: https://patch.msgid.link/20260710-b4-symana21-11221-imx-thermal-support-upstream-6-18-v3-0-db9fc2947c55@cn.bosch.com

Changes in v3:
- dt-bindings: add minimum/maximum (-28580/+28580) for
  temp-calibration-offset-millicelsius, as suggested by Conor Dooley
- Link to v2: https://patch.msgid.link/20260709-b4-symana21-11221-imx-thermal-support-upstream-6-18-v2-0-00ff72495e24@cn.bosch.com

Changes in v2:
- dt-bindings: Removed explicit `$ref: /schemas/types.yaml#/definitions/int32`
  for fsl,temp-calibration-offset-millicelsius; the `-millicelsius` suffix
  already resolves to int32-array via property-units.yaml (Rob).
- dt-bindings: Fixed example indentation.
- driver: Replaced C integer division (/) with DIV_ROUND_CLOSEST() in
  imx_set_alarm_temp() to prevent off-by-one alarm threshold mismatch that
  could cause IRQ storms on i.MX7D.
- driver: Added clamp() bounds check for alarm_value [0, 0x1ff] to avoid
  corrupting adjacent register fields (PANIC_ALARM).
- Link to v1: https://patch.msgid.link/20260709-b4-symana21-11221-imx-thermal-support-upstream-6-18-v1-0-00f88f42930b@cn.bosch.com

To: "Rafael J. Wysocki" <rafael@kernel.org>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
To: Zhang Rui <rui.zhang@intel.com>
To: Lukasz Luba <lukasz.luba@arm.com>
To: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzk+dt@kernel.org>
To: Conor Dooley <conor+dt@kernel.org>
To: Shawn Guo <shawnguo@kernel.org>
To: Sascha Hauer <s.hauer@pengutronix.de>
To: Pengutronix Kernel Team <kernel@pengutronix.de>
To: Fabio Estevam <festevam@gmail.com>
Cc: linux-pm@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: imx@lists.linux.dev
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org

---
Haoning CHENG (2):
      dt-bindings: thermal: imx: Document calibration offset property
      thermal/drivers/imx: Add calibration offset support

 .../devicetree/bindings/thermal/imx-thermal.yaml         |  9 +++++++++
 drivers/thermal/imx_thermal.c                            | 16 +++++++++++++---
 2 files changed, 22 insertions(+), 3 deletions(-)
---
base-commit: c50a940dcde35c647e097e89a9150003abd48329
change-id: 20260709-b4-symana21-11221-imx-thermal-support-upstream-6-18-a084984deb76

Best regards,
--  
Haoning CHENG <Haoning.CHENG@cn.bosch.com>

[PATCH v7 1/2] dt-bindings: thermal: imx: Document calibration offset property

[Haoning CHENG via B4 Relay]

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. The property is optional and the existing behaviour is kept
when it is omitted.

Update the binding example to show its usage.

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

[PATCH v7 2/2] thermal/drivers/imx: Add calibration offset support

[Haoning CHENG via B4 Relay]

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.

Read the optional fsl,temp-calibration-offset-millicelsius property from
DT and apply it to the i.MX6/6SX/7D calibration formulas. When the
property is not present, the default offset remains 0, preserving the
current behaviour.

Signed-off-by: Haoning Cheng <Haoning.CHENG@cn.bosch.com>
---
 drivers/thermal/imx_thermal.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
index 38c993d1bcb3..0a443e608957 100644
--- a/drivers/thermal/imx_thermal.c
+++ b/drivers/thermal/imx_thermal.c
@@ -207,6 +207,7 @@ struct imx_thermal_data {
 	struct regmap *tempmon;
 	u32 c1, c2; /* See formula in imx_init_calib() */
 	int temp_max;
+	s32 calibration_offset;
 	int alarm_temp;
 	int last_temp;
 	bool irq_enabled;
@@ -223,6 +224,7 @@ static void imx_set_panic_temp(struct imx_thermal_data *data,
 	struct regmap *map = data->tempmon;
 	int critical_value;
 
+	panic_temp -= data->calibration_offset;
 	critical_value = (data->c2 - panic_temp) / data->c1;
 
 	regmap_write(map, soc_data->panic_alarm_ctrl + REG_CLR,
@@ -239,11 +241,14 @@ static void imx_set_alarm_temp(struct imx_thermal_data *data,
 	int alarm_value;
 
 	data->alarm_temp = alarm_temp;
+	alarm_temp -= data->calibration_offset;
 
-	if (data->socdata->version == TEMPMON_IMX7D)
-		alarm_value = alarm_temp / 1000 + data->c1 - 25;
-	else
+	if (data->socdata->version == TEMPMON_IMX7D) {
+		alarm_value = DIV_ROUND_UP(alarm_temp, 1000) + data->c1 - 25;
+		alarm_value = clamp(alarm_value, 0, 0x1ff);
+	} else {
 		alarm_value = (data->c2 - alarm_temp) / data->c1;
+	}
 
 	regmap_write(map, soc_data->high_alarm_ctrl + REG_CLR,
 		     soc_data->high_alarm_mask);
@@ -277,6 +282,7 @@ static int imx_get_temp(struct thermal_zone_device *tz, int *temp)
 		*temp = (n_meas - data->c1 + 25) * 1000;
 	else
 		*temp = data->c2 - n_meas * data->c1;
+	*temp += data->calibration_offset;
 
 	/* Update alarm value to next higher trip point for TEMPMON_IMX6Q */
 	if (data->socdata->version == TEMPMON_IMX6Q) {
@@ -629,6 +635,10 @@ static int imx_thermal_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, data);
 
+	of_property_read_s32(dev->of_node,
+			     "fsl,temp-calibration-offset-millicelsius",
+			     &data->calibration_offset);
+
 	if (of_property_present(dev->of_node, "nvmem-cells")) {
 		ret = imx_init_from_nvmem_cells(pdev);
 		if (ret)

-- 
2.43.0

Re: [PATCH v7 2/2] thermal/drivers/imx: Add calibration offset support

[Frank Li]

On Mon, Jul 13, 2026 at 06:22:57PM +0800, Haoning CHENG via B4 Relay wrote:
> 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.
>
> Read the optional fsl,temp-calibration-offset-millicelsius property from
> DT and apply it to the i.MX6/6SX/7D calibration formulas. When the
> property is not present, the default offset remains 0, preserving the
> current behaviour.
>
> Signed-off-by: Haoning Cheng <Haoning.CHENG@cn.bosch.com>
> ---
>  drivers/thermal/imx_thermal.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
> index 38c993d1bcb3..0a443e608957 100644
> --- a/drivers/thermal/imx_thermal.c
> +++ b/drivers/thermal/imx_thermal.c
> @@ -207,6 +207,7 @@ struct imx_thermal_data {
>  	struct regmap *tempmon;
>  	u32 c1, c2; /* See formula in imx_init_calib() */
>  	int temp_max;
> +	s32 calibration_offset;
>  	int alarm_temp;
>  	int last_temp;
>  	bool irq_enabled;
> @@ -223,6 +224,7 @@ static void imx_set_panic_temp(struct imx_thermal_data *data,
>  	struct regmap *map = data->tempmon;
>  	int critical_value;
>
> +	panic_temp -= data->calibration_offset;
>  	critical_value = (data->c2 - panic_temp) / data->c1;
>
>  	regmap_write(map, soc_data->panic_alarm_ctrl + REG_CLR,
> @@ -239,11 +241,14 @@ static void imx_set_alarm_temp(struct imx_thermal_data *data,
>  	int alarm_value;
>
>  	data->alarm_temp = alarm_temp;
> +	alarm_temp -= data->calibration_offset;
>
> -	if (data->socdata->version == TEMPMON_IMX7D)
> -		alarm_value = alarm_temp / 1000 + data->c1 - 25;
> -	else
> +	if (data->socdata->version == TEMPMON_IMX7D) {
> +		alarm_value = DIV_ROUND_UP(alarm_temp, 1000) + data->c1 - 25;
> +		alarm_value = clamp(alarm_value, 0, 0x1ff);

Please use new patch update alarm_temp / 1000 to DIV_DOUND_UP() and clamp()
only and show reason why change this.

Frank

> +	} else {
>  		alarm_value = (data->c2 - alarm_temp) / data->c1;
> +	}
>
>  	regmap_write(map, soc_data->high_alarm_ctrl + REG_CLR,
>  		     soc_data->high_alarm_mask);
> @@ -277,6 +282,7 @@ static int imx_get_temp(struct thermal_zone_device *tz, int *temp)
>  		*temp = (n_meas - data->c1 + 25) * 1000;
>  	else
>  		*temp = data->c2 - n_meas * data->c1;
> +	*temp += data->calibration_offset;
>
>  	/* Update alarm value to next higher trip point for TEMPMON_IMX6Q */
>  	if (data->socdata->version == TEMPMON_IMX6Q) {
> @@ -629,6 +635,10 @@ static int imx_thermal_probe(struct platform_device *pdev)
>
>  	platform_set_drvdata(pdev, data);
>
> +	of_property_read_s32(dev->of_node,
> +			     "fsl,temp-calibration-offset-millicelsius",
> +			     &data->calibration_offset);
> +
>  	if (of_property_present(dev->of_node, "nvmem-cells")) {
>  		ret = imx_init_from_nvmem_cells(pdev);
>  		if (ret)
>
> --
> 2.43.0
>
>
>

Re: [PATCH v7 2/2] thermal/drivers/imx: Add calibration offset support

[Lukasz Luba]

On 7/13/26 11:22, Haoning CHENG via B4 Relay wrote:
> 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.
> 
> Read the optional fsl,temp-calibration-offset-millicelsius property from
> DT and apply it to the i.MX6/6SX/7D calibration formulas. When the
> property is not present, the default offset remains 0, preserving the
> current behaviour.

s/behaviour/behavior/

Also, you can add a description in this patch header with an example
how this is going to be calculated. The full mechanism is split
into two components: this driver and the thermal framework.

When the IRQ (which was programmed for e.g. 'panic temp' value)
is triggered then thermal fwk is kicked. In that the 'get_temp'
will be called.

What this change effectively does is:
- program the IRQ firing temp level higher (based on dt example)
- provide the temp value lower to thermal fwk
then you don't touch other stuff which is generic in this
thermal scope (like trip points).

It's kind of tricky to grasp and I would suggest to describe it
somewhere. These are popular chips and many boards use them,
so many engineers might miss this bit.

> 
> Signed-off-by: Haoning Cheng <Haoning.CHENG@cn.bosch.com>
> ---
>   drivers/thermal/imx_thermal.c | 16 +++++++++++++---
>   1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
> index 38c993d1bcb3..0a443e608957 100644
> --- a/drivers/thermal/imx_thermal.c
> +++ b/drivers/thermal/imx_thermal.c
> @@ -207,6 +207,7 @@ struct imx_thermal_data {
>   	struct regmap *tempmon;
>   	u32 c1, c2; /* See formula in imx_init_calib() */
>   	int temp_max;
> +	s32 calibration_offset;
>   	int alarm_temp;
>   	int last_temp;
>   	bool irq_enabled;
> @@ -223,6 +224,7 @@ static void imx_set_panic_temp(struct imx_thermal_data *data,
>   	struct regmap *map = data->tempmon;
>   	int critical_value;
>   
> +	panic_temp -= data->calibration_offset;
>   	critical_value = (data->c2 - panic_temp) / data->c1;
>   
>   	regmap_write(map, soc_data->panic_alarm_ctrl + REG_CLR,
> @@ -239,11 +241,14 @@ static void imx_set_alarm_temp(struct imx_thermal_data *data,
>   	int alarm_value;
>   
>   	data->alarm_temp = alarm_temp;
> +	alarm_temp -= data->calibration_offset;
>   
> -	if (data->socdata->version == TEMPMON_IMX7D)
> -		alarm_value = alarm_temp / 1000 + data->c1 - 25;
> -	else
> +	if (data->socdata->version == TEMPMON_IMX7D) {
> +		alarm_value = DIV_ROUND_UP(alarm_temp, 1000) + data->c1 - 25;
> +		alarm_value = clamp(alarm_value, 0, 0x1ff);

This doesn't belong to the $subject. Needs extra patch.

> +	} else {
>   		alarm_value = (data->c2 - alarm_temp) / data->c1;
> +	}
>   
>   	regmap_write(map, soc_data->high_alarm_ctrl + REG_CLR,
>   		     soc_data->high_alarm_mask);
> @@ -277,6 +282,7 @@ static int imx_get_temp(struct thermal_zone_device *tz, int *temp)
>   		*temp = (n_meas - data->c1 + 25) * 1000;
>   	else
>   		*temp = data->c2 - n_meas * data->c1;
> +	*temp += data->calibration_offset;
>   
>   	/* Update alarm value to next higher trip point for TEMPMON_IMX6Q */
>   	if (data->socdata->version == TEMPMON_IMX6Q) {
> @@ -629,6 +635,10 @@ static int imx_thermal_probe(struct platform_device *pdev)
>   
>   	platform_set_drvdata(pdev, data);
>   
> +	of_property_read_s32(dev->of_node,
> +			     "fsl,temp-calibration-offset-millicelsius",
> +			     &data->calibration_offset);
> +


No bounds check here or debug message?
Playing with raw registers which handle thermal safety net it's kind of
risky IMO (a typo by one digit and the board dies).
Done once in the setup code won't harm performance and something which
goes to the DT schema is quite stable to reuse.

Regards,
Lukasz