[lm-sensors] testing w83627hf treiber?

Jean Delvare khali at linux-fr.org
Mon Dec 4 09:06:02 CET 2006

Hi Thomas,

(Huh, please don't use URLs as post subjects.)

On Sun, 03 Dec 2006 21:20:01 +0100, Thomas Dohl wrote:
> I've found a strange bug or what ever in the Module. :)
> I'll try to explain it.
> If I boot Linux with the module "w83627hf", everything
> is ok. But if I load the module with the workaround, like
> "modprobe w83627hf reset=1" I get a 23°C higher temperature
> of the second sensor.
> At boottime:
> temp1: 34°C
> temp2: 33°C
> after modprobe with reset=1
> temp1: 34°C
> temp2: 56°C (23°C more than it is)
> This doesn't change after rmmod w83627hf, modprobe w83627hf.
> Only after reboot, the values return to normal.
> What could that be?

Easy. The W83627*F chips have temperature offset registers. The BIOS
must write an offset for the temp2 (CPU?) temperature sensor, to
account for a different thermal diode model for example, or just to
make it look cooler to the user... When the w83627hf driver resets the
chip, the offset is reset to 0 as well, so you get the "raw" reading

See, this is exactly the reason why we don't reset the chip by default:
to preserve BIOS settings.

Jean Delvare

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