after running 'sensors-detect' command, kernel modules controlling fan speed should be loaded.
here is an occasion with 'Nuvoton NCT6102D/NCT6104D/NCT6106D Super IO Sensors' detected.
as nct6775 document said:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | #/sys/class/hwmon/hwmon4 pwm[1-7] - this file stores PWM duty cycle or DC value (fan speed) in range: 0 (lowest speed) to 255 (full) pwm[1-7]_enable - this file controls mode of fan/temperature control: * 0 Fan control disabled (fans set to maximum speed) * 1 Manual mode, write to pwm[0-5] any value 0-255 * 2 "Thermal Cruise" mode * 3 "Fan Speed Cruise" mode * 4 "Smart Fan III" mode (NCT6775F only) * 5 "Smart Fan IV" mode ... |
ps1. if set pwm[1-7]_enable to 0, we will not be able to change it to other value, unless reboot linux.
ps2. I still can't find a common way to turn off fans using ipmitool.
IPMI: Intelligent Platform Management Interface
BMC: Baseboard Management Controller
FRU: Field Replaceable Unit
refer to:
[linux-kernel-src-root]/Documentation/hwmon/nct6775.rst
https://bbs.archlinux.org/viewtopic.php?id=225349