Don't know if this answers are sufficient - here are links :
A workaround in arch Linux - but backlight is here only explained at edge.
https://wiki.archlinux.org/index.php/Intel_Graphics
And here is more detailed explanation concerning intel 945GM :
http://linux.die.net/man/4/intel
There beyond "Output Configuration" are the options of backlight.
As you can read there - brightness and backlight are two different things which can be adjusted.
xrandr --prop
delivers the current set datas.
Perhaps it is of matter if you install saucy-kernel 3.10 ( download it at ubuntu ) - only in case if you still use kernel 3.2.0-49 ? ( if this does not work, then you still have kernel 3.2.0-49 in your system to go back there ) :
http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.10-saucy
So - don't know if Kernel 3.10 is necessary for below additions - you can test without danger after downloaded 3.10 suiting to your 64 or 32 processor :
sudo dpkg -i linux-*.deb
Sorry - now have seen that there is an extra package besides xrandr - it
is called xbacklight
It is not installed by default:
sudo apt-get install xbacklight
xbacklight -get
delivers the current set value.
According to man xbacklight you can set it with:
xbacklight -set (here decimal value in percent !)
There is a special brightness for xbacklight to be set with:
xbacklight -inc (here decimal value increases in percent !)
and
xbacklight -dec (here decimal value decreases in persent !)
lowers the value down again - in case value was set too high.
Is your question answered ? - Let me know !
I got a fix for my dell 5521 laptop, working for Ubuntu 14.04 but will work for kernels v3.13+.
Open /etc/default/grub
sudo nano /etc/default/grub
to change the line
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
to
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=1"
then save and exit and
run
sudo update-grub
then reboot
The explanation is that ACPI adds its own back light control even if one is already present which is intel_backlight
, adding this line forces CPI to use the Intel back light.
Best Answer
Try to change the file
brightness
in both directories (interfaces)acpi_video0
andintel_backlight
via the following command:If one of the changes affects your backlight create (if not exists)
/etc/X11/xorg.conf
or better/usr/share/X11/xorg.conf.d/20-intel.conf
and add the following lines where "xxx" belongs to your interface:Restart your computer and see if works now. You can read also here.