I have a BIOSTAR P4M900-M7 FE motherboard, which has a VIA P4M900 Chrome9 chipset (yes, old, but powerful for basic usage, everything I need). The point is that I made a new installation of Ubuntu Bionic 18.04.3 (Ubuntu MATE specifically) and installed the free driver for this type of chips, "X.Org X server OpenChrome display driver" (xserver-xorg-video-openchrome package) from the repository. The driver works perfectly, the performance is good (even with compiz and HD videos), but the problem is that I can't change the brightness (essential for me). I already tried with xrandr:
user@os:~$ xrandr --current
Screen 0: minimum 320 x 200, current 1280 x 720, maximum 2044 x 2048
VGA-1 connected primary 1280x720+0+0 (normal left inverted right x axis y axis) 477mm x 268mm
1920x1080 60.00 + 60.00
1680x1050 59.95
1400x1050 59.98
1600x900 60.00
1280x1024 75.02 60.02
1440x900 59.89
1280x800 59.81
1152x864 75.00
1280x720 60.00*
1024x768 75.03 60.00
800x600 75.00 60.32
640x480 75.00 59.94
720x400 70.08
and:
user@os:~$ xrandr --output VGA-1 --brightness 0.5
user@os:~$
But as you can see, absolutely nothing happens, not even a message or error. The same goes for the gamma command:
user@os:~$ xrandr --output VGA-1 --gamma 0.5:0.5:1.0
user@os:~$
However, I tried changing the resolution with:
user@os:~$ xrandr --output VGA-1 --mode 1280x720
and it works perfectly, the resolution is changed without problems.
I did some research and it seems that OpenChorme is configured through the file xorg.conf but, apparently, this file no longer exists as such, but now there is a directory, /usr/share/X11/xorg.conf.d, where they are graphics controller settings separately. The point is that I can't find a file that refers to openchrome anywhere.
xrandr works, because the resolution is changed perfectly with --mode command, but what happens with --brightness and --gamma, why nothing happens? I need a way to change the brightness.
Any help would be greatly appreciated.
