Asus K55VJ - Brightness/backlight issue

sPHERE · 2012-12-25 19:37:59

Hi,

I have a brand new Asus K55VJ laptop, and everything runs great besides one thing.

After I upgraded my kernel from default to linux-ck, I have lost the ability to change backlight brightness with xbacklight.
(I dont use the intended brightness-keys as the dont get recognized by either of the kernels, so I binded some other keys for it).
So I tried installing "light" from AUR, but it only work as root. Xbacklight doesnt report any error while root or regular user, and doesnt work as root either.

I have tried both with and without "acpi_backlight=vendor" and "legacy", without any change.

I can echo to my brightness-file in /sys/class/backlight/intel_backlight/brightness file as root, but not as regular user.

I tried a dirty? solution and just changed the permissions of the file, but they dont survive a reboot.

If anybody has any clue as to what's going on I'd like that very much.

Also, if anybody actually has this laptop It'd be great to hear if anyone has gotten the intended brightness keys to function.

This is the error message from Light:

[petterk@petterk-archlinux ~]$ light 50
Light 0.7 - Fredrik Haikarainen
Fetching controllers..
Warning: Controllerfile of 'asus-nb-wmi' is not writable. Will ignore this controller.
Warning: Controllerfile of 'intel_backlight' is not writable. Will ignore this controller.
Found 'asus-nb-wmi', but ignoring
Found 'intel_backlight', but ignoring
No okay controller found, check your permissions or try to run as root.

Last edited by sPHERE (2012-12-25 20:15:15)

westmn · 2012-12-27 13:47:33

I'm in the same boat, I was going to make a systemd service that would change the permissions for the brightness file at each boot but I haven't gotten around to it.

sPHERE · 2012-12-28 13:53:52

Yeah, seems like that may be the only option left.

I was hoping someone would know how to actually solve the issue instead of working around it...

But thanks for your reply, appreciated.

sPHERE · 2012-12-30 20:21:02

Anyone?

dif · 2013-01-04 01:51:25

Try my solution. I wrote two simple scripts:
(1) brightness_down.sh

#!/bin/bash
f=/sys/class/backlight/acpi_video1/brightness
b=$(cat $f)
if (( b > 0 )) ; then 
	((b--))
	sudo -u root chmod o+w $f
	echo $b > $f
	sudo -u root chmod o-w $f
fi

(2) brighteness_up.sh

#!/bin/bash
f=/sys/class/backlight/acpi_video1/brightness
b=$(cat $f)
if (( b < 9 )) ; then 
	((b++))
	sudo -u root chmod o+w $f
	echo $b > $f
	sudo -u root chmod o-w $f
fi

I added two lines to my /etc/sudoers:

dif ALL = NOPASSWD: /home/dif/bin/brightness_up.sh
dif ALL = NOPASSWD: /home/dif/bin/brightness_down.sh

so that I can use them without a password.
Finally, I just bound them with the <ctrl>+<f5> and <ctrl>+<f6> buttons, using a standard gnome keyboard settings.

You can check the maximum and minimum brightness values to be on the safe side. In my Asus K55VM they are 0 and 10.
You may modify the scripts to make them more universal by checking automatically the limit brightness values, but it would be overkill in my opinion.
Modify the f variable, too, if necessary.

Hope this helps.

sPHERE · 2013-01-04 14:35:47

hey man, thanks for your reply.

I made a similar sollution myself actually.

I added the nopasswd lines in my etc/sudoers file so the program "light" can be launched as root without needing to enter the root password, and bound the corresponding commands to my Fn+F3 and Fn+F4.

I assume your K55VM's original brightness keys dont work either?

In my K55VJ the only keys that dont work are the brightness and the wifi-keys, but that doesnt really bother me.

Also, my maximum brightness is 4882 lol. Quite a number there.

dif · 2013-01-04 19:09:58

That's right. The original brightness keys do not work. Nor does switching off the touchpad. The multimedia buttons under the arrow keys don't work either. Surprisingly, the calculator key works under the enter button. As a matter of fact, I do not care about the Fn keys that do not work. All I need is the brightness keys.

The wi-fi key works. Unfortunately . It is right next to the e-mail client key, and I switched off my wi-fi connection by mistake a few times until I'd had enough and made <alt>+<m> my e-mail key.

Arch Linux

#1 2012-12-25 19:37:59

Asus K55VJ - Brightness/backlight issue

#2 2012-12-27 13:47:33

Re: Asus K55VJ - Brightness/backlight issue

#3 2012-12-28 13:53:52

Re: Asus K55VJ - Brightness/backlight issue

#4 2012-12-30 20:21:02

Re: Asus K55VJ - Brightness/backlight issue

#5 2013-01-04 01:51:25

Re: Asus K55VJ - Brightness/backlight issue

#6 2013-01-04 14:35:47

Re: Asus K55VJ - Brightness/backlight issue

#7 2013-01-04 19:09:58

Re: Asus K55VJ - Brightness/backlight issue

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