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

Zhang, Rui rui.zhang at intel.com
Thu Apr 10 02:31:18 CEST 2008

On Thu, 2008-04-10 at 03:40 +0800, Jean Delvare wrote:
> 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
> expected.
> 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.
Yes, you're right.
A fix will be send out together with the refreshed generic thermal hwmon
conversion patches. ;)

> Thanks,
> --
> Jean Delvare

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