Arch Linux

justdanyul

Member

Registered: 2011-09-29

Posts: 137

Fan controls, BIOS versus sysfs

Hi all,

I have a question that I'm hoping somebody here could answer. In short, if I put a fan in manual mode using the sysfs-interface, as follows

echo 1 > /sys/class/hwmon/hwmon9/pwm1_enable

I can then manually set the fan to 100% as follows

echo 255 > /sys/class/hwmon/hwmon9/pwm1

Now to my questions

1. it seems that this have now efficiently taken precedence over the fan-curves in BIOS, but this is an assumption. Could anybody validate that this is the case? 

2. is there any way to give control back to the BIOS? If I set the fan back to automatic with the sysfs-interface. It seems to just go to the fan_min value. as opposed to allow the bios to control it again.