Re: [PATCH v1] thermal: core: Do not fail cdev registration because of invalid initial state
From: Daniel Lezcano
Date: Thu Jun 06 2024 - 09:07:50 EST
On 05/06/2024 21:17, Rafael J. Wysocki wrote:
From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
It is reported that commit 31a0fa0019b0 ("thermal/debugfs: Pass cooling
device state to thermal_debug_cdev_add()") causes the ACPI fan driver
to fail probing on some systems which turns out to be due to the _FST
control method returning an invalid value until _FSL is first evaluated
for the given fan. If this happens, the .get_cur_state() cooling device
callback returns an error and __thermal_cooling_device_register() fails
as uses that callback after commit 31a0fa0019b0.
Arguably, _FST should not return an inavlid value even if it is
evaluated before _FSL, so this may be regarded as a platform firmware
issue, but at the same time it is not a good enough reason for failing
the cooling device registration where the initial cooling device state
is only needed to initialize a thermal debug facility.
Accordingly, modify __thermal_cooling_device_register() to pass a
negative state value to thermal_debug_cdev_add() instead of failing
if the initial .get_cur_state() callback invocation fails and adjust
the thermal debug code to ignore negative cooling device state values.
Fixes: 31a0fa0019b0 ("thermal/debugfs: Pass cooling device state to thermal_debug_cdev_add()")
Closes: https://lore.kernel.org/linux-acpi/20240530153727.843378-1-laura.nao@xxxxxxxxxxxxx
Reported-by: Laura Nao <laura.nao@xxxxxxxxxxxxx>
Tested-by: Laura Nao <laura.nao@xxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
As it is a driver issue, it should be fixed in the driver, not in the
core code. The resulting code logic in the core is trying to deal with
bad driver behavior, it does not really seem appropriate.
The core code has been clean up from the high friction it had with the
legacy ACPI code. It would be nice to continue it this direction.
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