laptop@laptop-X540SA:~$ sudo pwmconfig
# pwmconfig revision 6243 (2014-03-20)
This program will search your sensors for pulse width modulation (pwm)
controls, and test each one to see if it controls a fan on
your motherboard. Note that many motherboards do not have pwm
circuitry installed, even if your sensor chip supports pwm.

We will attempt to briefly stop each fan using the pwm controls.
The program will attempt to restore each fan to full speed
after testing. However, it is ** very important ** that you
physically verify that the fans have been to full speed
after the program has completed.

Found the following devices:
   hwmon0 is acpitz
   hwmon1 is soc_dts0
   hwmon2 is soc_dts1
   hwmon3 is coretemp
   hwmon4 is asus

Found the following PWM controls:
   hwmon4/pwm1           current value: -1
hwmon4/pwm1 is currently setup for automatic speed control.
In general, automatic mode is preferred over manual mode, as
it is more efficient and it reacts faster. Are you sure that
you want to setup this output for manual control? (n)
There are no usable PWM outputs.