Re: [PATCH 2/5] thermal/drivers/mediatek/lvts: Disable Stage 3 thermal threshold

From: AngeloGioacchino Del Regno
Date: Tue Nov 26 2024 - 04:54:21 EST


Il 25/11/24 22:20, Nícolas F. R. A. Prado ha scritto:
The Stage 3 thermal threshold is currently configured during
the controller initialization to 105 Celsius. From the kernel
perspective, this configuration is harmful because:
* The stage 3 interrupt that gets triggered when the threshold is
crossed is not handled in any way by the IRQ handler, it just gets
cleared. Besides, the temperature used for stage 3 comes from the
sensors, and the critical thermal trip points described in the
Devicetree will already cause a shutdown when crossed (at a lower
temperature, of 100 Celsius, for all SoCs currently using this
driver).
* The only effect of crossing the stage 3 threshold that has been
observed is that it causes the machine to no longer be able to enter
suspend. Even if that was a result of a momentary glitch in the
temperature reading of a sensor (as has been observed on the
MT8192-based Chromebooks).

For those reasons, disable the Stage 3 thermal threshold configuration.

Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Hsin-Te Yuan <yuanhsinte@xxxxxxxxxxxx>
Closes: https://lore.kernel.org/all/20241108-lvts-v1-1-eee339c6ca20@xxxxxxxxxxxx/
Fixes: f5f633b18234 ("thermal/drivers/mediatek: Add the Low Voltage Thermal Sensor driver")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>