How can I disable asus-nb-wmi when using battery power mode?

Question

I'm trying to improve the battery life of my Asus U32U notebook. I'm running Ubuntu 12.04 64bit and using powertop it shows the following:

PowerTOP 1.97     Overview   Idle stats   Frequency stats   Device stats   Tunables   

Summary: 311.6 wakeups/second,  0.0 GPU ops/second and 0.0 VFS ops/sec

Power est.      Usage       Events/s    Category       Description
  6.29 W    100.0%                      Device         Radio device: asus-nb-wmi
  1.19 W    100.0%                      Device         Display backlight
    0 mW     49.3 ms/s      42.8        Process        compiz
    0 mW     19.5 ms/s      51.4        Process        /usr/bin/X :0 -auth /var/run/li
    0 mW     10.3 ms/s      16.8        Process        gnome-terminal
    0 mW      5.5 ms/s     118.1        Interrupt      PS/2 Touchpad / Keyboard / Mous
    0 mW      2.0 ms/s      37.0        Interrupt      [45] fglrx[0]@PCI:0:1:0
    0 mW      1.6 ms/s       0.4        Process        powertop
    0 mW      1.5 ms/s       1.1        Process        /usr/lib/unity/unity-panel-serv
    0 mW      1.0 ms/s       4.5        Timer          tick_sched_timer
    0 mW      1.0 ms/s       9.3        Process        syndaemon -i 2.0 -K -R -t
    0 mW      0.9 ms/s      20.3        Timer          hrtimer_wakeup
    0 mW      0.8 ms/s       0.2        Process        [flush-ecryptfs-]
    0 mW      0.7 ms/s       0.9        Process        /usr/lib/gnome-settings-daemon/
    0 mW    697.3 µs/s       0.2        kWork          rfkill_poll

According to this Ubuntu community help page the asus-nb-wmi driver is responsible for implementing the function keys, something I can definitely live without if it means I will get longer battery sessions.

So I would like to know if its possible to disable the asus-nb-wmi when not plugged in to AC power, and if so, how.

Solution 1

I have a similar asus laptop. However, on mine it's called "asus_nb_wmi". I just use

sudo rmmod asus_nb_wmi

to disable, and then

sudo modprobe asus_nb_wmi

if i want to reenable it and be able to use function keys to control the volume level again.

Solution 2

Add this line to your /etc/modprobe.d/blacklist.conf:

blacklist asus-nb-wmi

That will disable loading asus-nb-wmi on boot.

Comments

[Anwar]

Well, can you update the answer with steps of how can someone turn off the backlight?

[Bill McCracken]

@Anwar You just turn down the backlight using the appropriate function key on your keyboard, or shortcut in your OS if available. I don't know how to do it by scripting.

[Anwar]

You used the fn keys?

[Bill McCracken]

yes. obviously you cannot do this after you remove asus-nb-wmi, because that renders the function keys inoperable. in my experience, it was sufficient to turn down the backlight and then there was no need to remove asus-nb-wmi. YMMV