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docs: thermal: sync hardware protection doc with code

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Originally, the thermal framework's only hardware protection action was to
trigger a shutdown.  This has been changed a little over a year ago to
also support rebooting as alternative hardware protection action.

Update the documentation to reflect this.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-3-e1c09b090c0c@pengutronix.de
Fixes: 62e79e38b257 ("thermal/thermal_of: Allow rebooting after critical temp")
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Cc: Benson Leung <bleung@chromium.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matteo Croce <teknoraver@meta.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Herring (Arm) <robh@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ahmad Fatoum 2025-02-17 21:39:43 +01:00 committed by Andrew Morton
parent bbf0ec4f57
commit 06eaeaee5b
1 changed files with 14 additions and 11 deletions
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25
Documentation/driver-api/thermal/sysfs-api.rst
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@ -413,18 +413,21 @@ This function serves as an arbitrator to set the state of a cooling
device. It sets the cooling device to the deepest cooling state if
possible.
5. thermal_emergency_poweroff
=============================
5. Critical Events
==================
On an event of critical trip temperature crossing the thermal framework
shuts down the system by calling hw_protection_shutdown(). The
hw_protection_shutdown() first attempts to perform an orderly shutdown
but accepts a delay after which it proceeds doing a forced power-off
or as last resort an emergency_restart.
On an event of critical trip temperature crossing, the thermal framework
will trigger a hardware protection power-off (shutdown) or reboot,
depending on configuration.
At first, the kernel will attempt an orderly power-off or reboot, but
accepts a delay after which it proceeds to do a forced power-off or
reboot, respectively. If this fails, ``emergency_restart()`` is invoked
as last resort.
The delay should be carefully profiled so as to give adequate time for
orderly poweroff.
orderly power-off or reboot.
If the delay is set to 0 emergency poweroff will not be supported. So a
carefully profiled non-zero positive value is a must for emergency
poweroff to be triggered.
If the delay is set to 0, the emergency action will not be supported. So a
carefully profiled non-zero positive value is a must for the emergency
action to be triggered.