I'm trying to regulate the fans in my VIA A2000 barebone (VIA VX800 chipset) but the mainboard doesn't seem to allow this.
I've already installed the latest kernel (2.6.29-RC4), lm-sensors package (3.10) and ran sensors-detect. It seems that the hardware has been correctly identified and set up:
Adapter: SMBus Via Pro adapter at 0500
in0: +1.09 V (min = +0.00 V, max = +2.04 V)
in1: +1.82 V (min = +0.00 V, max = +2.04 V)
in2: +1.09 V (min = +0.00 V, max = +2.04 V)
fan1: 5037 RPM (min = 5037 RPM, div = 4)
fan2: 1804 RPM (min = 1804 RPM, div = 4)
temp1: +70.0°C (high = +50.0°C, hyst = +49.0°C)
temp2: +37.0°C (high = +50.0°C, hyst = +49.0°C)
But when I try to run pwmconfig, no speed changes occur when adjusting the pwm values and the fans keep rotating at full speed.
Manually echoing values to /sys/class/hwmon/hwmon0/device/pwmX also doesn't affect the fan speed (although the PWM value does change).
After looking at the the sources of the viapro-module, I've seen that the device should also support DC-regulated change of fan speed (pwmX_mode 0 instead of 1). But when I try to set the value to 0, the system accepts it but an immediate reading of the value returns 1 again :-(
What might be the reason? Is it a BIOS related bug or has VIA simply disabled any write-access to the i2c-bus?