[lm-sensors] Temperature in generic thermal zone not updated

Jean Delvare khali at linux-fr.org
Wed Apr 9 21:40:07 CEST 2008

Hi Rui,

I am testing your generic thermal zone driver on my old Sony laptop
(Vaio PCG-GR214EP) and I have noticed that the temperature reported by
the generic thermal zone interface
(/sys/class/thermal/thermal_zone0/temp) isn't updated. The reported
value is always the same, until I read
from /proc/acpi/thermal_zone/ATF0/temperature. After that the value
in /sys/class/thermal/thermal_zone0/temp matches the one reported
in /proc/acpi/thermal_zone/ATF0/temperature, but doesn't change again
until the next access to /proc/acpi/thermal_zone/ATF0/temperature.

This is with polling disabled on the ACPI thermal zone (the default on
my system). If I set polling to 2 seconds, then reading
from /sys/class/thermal/thermal_zone0/temp shows changing values as

So it seems to me that reading
from /proc/acpi/thermal_zone/ATF0/temperature updates the temperature
value when polling is disabled, while reading
from /sys/class/thermal/thermal_zone0/temp only returns a cached value.
Is it correct? I think that the generic thermal driver should be fixed
to update the temperature values properly.

Jean Delvare

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