diff mbox series

[v11,1/4] dt-bindings: thermal-zones: Document critical-action

Message ID 20231119130551.2416869-1-festevam@gmail.com
State Not Applicable
Headers show
Series [v11,1/4] dt-bindings: thermal-zones: Document critical-action | expand

Checks

Context Check Description
robh/checkpatch success
robh/patch-applied success
robh/dtbs-check warning build log
robh/dt-meta-schema success

Commit Message

Fabio Estevam Nov. 19, 2023, 1:05 p.m. UTC 
From: Fabio Estevam <festevam@denx.de>

Document the critical-action property to describe the thermal action
the OS should perform after the critical temperature is reached.

The possible values are "shutdown" and "reboot".

The motivation for introducing the critical-action property is that
different systems may need different thermal actions when the critical
temperature is reached.

For example, in a desktop PC, it is desired that a shutdown happens
after the critical temperature is reached.

However, in some embedded cases, such behavior does not suit well,
as the board may be unattended in the field and rebooting may be a
better approach.

The bootloader may also benefit from this new property as it can check
the SoC temperature and in case the temperature is above the critical
point, it can trigger a shutdown or reboot accordingly.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
Changes since v10:
- None

 .../bindings/thermal/thermal-zones.yaml          | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Comments

Daniel Lezcano Nov. 29, 2023, 12:06 p.m. UTC | #1 
On 19/11/2023 14:05, Fabio Estevam wrote:
> From: Fabio Estevam <festevam@denx.de>
> 
> Introduce thermal_zone_device_critical_reboot() to trigger an
> emergency reboot.
> 
> It is a counterpart of thermal_zone_device_critical() with the
> difference that it will force a reboot instead of shutdown.
> 
> The motivation for doing this is to allow the thermal subystem
> to trigger a reboot when the temperature reaches the critical
> temperature.
> 
> Signed-off-by: Fabio Estevam <festevam@denx.de>
> ---

[ ... ]

> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index cee814d5d1ac..3644326b18ac 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -361,6 +361,7 @@ int thermal_zone_get_offset(struct thermal_zone_device *tz);
>   int thermal_zone_device_enable(struct thermal_zone_device *tz);
>   int thermal_zone_device_disable(struct thermal_zone_device *tz);
>   void thermal_zone_device_critical(struct thermal_zone_device *tz);
> +void thermal_zone_device_critical_reboot(struct thermal_zone_device *tz);

It is more relevant to keep it private to the thermal core as there is 
no user of it except in the thermal-of. IOW in thermal_core.h

[ ... ]
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
index 4a8dabc48170..dbd52620d293 100644
--- a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
+++ b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
@@ -75,6 +75,22 @@  patternProperties:
           framework and assumes that the thermal sensors in this zone
           support interrupts.
 
+      critical-action:
+        $ref: /schemas/types.yaml#/definitions/string
+        description: |
+          The action the OS should perform after the critical temperature is reached.
+          By default the system will shutdown as a safe action to prevent damage
+          to the hardware, if the property is not set.
+          The shutdown action should be always the default and preferred one.
+          Choose 'reboot' with care, as the hardware may be in thermal stress,
+          thus leading to infinite reboots that may cause damage to the hardware.
+          Make sure the firmware/bootloader will act as the last resort and take
+          over the thermal control.
+
+        enum:
+          - shutdown
+          - reboot
+
       thermal-sensors:
         $ref: /schemas/types.yaml#/definitions/phandle-array
         maxItems: 1