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#1 2012-09-11 09:04:35

JayCie
Member
Registered: 2012-09-11
Posts: 4

[backlight] Can't make it work

Hi Arch-users !

I recently bought an Asus N56VM ( http://www.asus.com/Notebooks/Multimedi … ifications ).

=> optimus is working fine using Bumblebee
=> sound is working fine (alsa + jackd)
=> touchpad is working fine adding clickpad option in /etc/X11/xorg.conf.d10-synaptics.conf
=> keybord-backlight is working fine with https://github.com/ktoso/g73-keyboard-backlight-sh

The only problem I still have is the control of backlight of the screen.
I looked at the wiki page ( https://wiki.archlinux.org/index.php/Backlight ) and here is a summary :

The ACPI kernel interface for interacting with the backlight is typically be located here : /sys/class/backlight/acpi_video0/

Before, /sys/class/baklight was empty. Since i added "acpi_osi=Linux acpi_backlight=vendor" in /etc/default/grub, i've a folder here named "asus-nb-wmi", but i dont know if it is the "good" folder... Let's assume it is the good folder.

I go in /sys/class/backlight/asus-nb-wmi, and i try to edit brightness

# cat /sys/class/backlight/asus-nb-wmi/max_brightness
10
# echo 5 > /sys/class/backlight/asus-nb-wmi/brightness

Problem : This command "works" because it doesn't return an error, but it does not affect my screen => the brightness is maximum.
Even if I set /sys/class/backlight/asus-nb-wmi/brightness to 0, my screen is shining sad !

I also tried to use xbacklight, but as you can see, it doesn't work properly either.

# xbacklight
No outputs have backlight property

So my question is simple : What can i do in order to control the backlight brightness ?
Feel free to give me all advices you can have : I'm interested in !

Thank you in advance <3 !
Jc

Last edited by JayCie (2012-09-11 14:21:00)

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#2 2012-09-12 10:48:57

dontbugme
Banned
Registered: 2011-11-04
Posts: 166
Website

Re: [backlight] Can't make it work

Check if /sys/class/backlight is empty, if you remove either the acpi_osi or acpi_backlight=vendor. My assumption is that one of the 2 kernel parameters isn't necessary.

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#3 2012-09-12 11:45:37

brebs
Member
Registered: 2007-04-03
Posts: 3,441

Re: [backlight] Can't make it work

See previous thread.

You haven't tried "=legacy"? That's what I use, with nvidia.

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#4 2012-09-12 12:39:47

JayCie
Member
Registered: 2012-09-11
Posts: 4

Re: [backlight] Can't make it work

Thanks a lot for responding ! smile
Both of your responses are related with GRUB_CMDLINE_LINUX_DEFAULT, so let me show you exactly what is my config, and what i planned to do.

1) Currently, I have :

GRUB_CMDLINE_LINUX_DEFAULT="quiet elevator=deadline nomodeset acpi_osi=Linux acpi_backlight=vendor"

result : backlight is not working even if I have a folder "/sys/class/backlight/asus-nb-wmi"

2) I will first try :

GRUB_CMDLINE_LINUX_DEFAULT="quiet elevator=deadline nomodeset acpi_backlight=vendor"

=> result : same as 1)

3) then i will try :

GRUB_CMDLINE_LINUX_DEFAULT="quiet elevator=deadline nomodeset acpi_osi=Linux acpi_backlight=legacy"

=> result : the folder "/sys/class/backlight/asus-nb-wmi" is no more here. Of course, backlight is not working.

4) finaly, I will try :

GRUB_CMDLINE_LINUX_DEFAULT="quiet elevator=deadline nomodeset acpi_backlight=legacy"

=> result : same as 3)

I will try to test this today, and I will edit this post at each step in order to show my results.
When I'm done, I will post another message telling the result of my tests.

Thank you a lot for responding, and giving me advices. If you have another ideas, dont hesitate to post. smile

Last edited by JayCie (2012-09-12 12:53:10)

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#5 2012-09-12 12:57:28

JayCie
Member
Registered: 2012-09-11
Posts: 4

Re: [backlight] Can't make it work

So here is my conclusion :

1) adding/removing acpi_osi=Linux is not affecting the final result
2) acpi_backlight=legacy removes the folder  "/sys/class/backlight/asus-nb-wmi"
3) acpi_backlight=vendor addsthe folder "/sys/class/backlight/asus-nb-wmi", but backlight still not working.

Any other ideas ? sad

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#6 2012-09-12 13:06:40

brebs
Member
Registered: 2007-04-03
Posts: 3,441

Re: [backlight] Can't make it work

Maybe you will need to debug your BIOS with iasl.

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#7 2012-09-12 14:44:54

JayCie
Member
Registered: 2012-09-11
Posts: 4

Re: [backlight] Can't make it work

Wow Oo ! I will look at this, but i'm a bit scared by the idea of trying to "debug my bios" !

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#8 2012-09-12 18:14:22

zxz
Member
Registered: 2012-09-12
Posts: 4

Re: [backlight] Can't make it work

Try installing nvidiabl from AUR.

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