Hi everybody! I am currently setting up Ubuntu Linux 12.04 Precise Pangolin on my Samsung laptop/notebook 700Z3A. I added the PPA and installed samsung-tools and samsung-laptop through it. It got the light lensor for the keyboard backlight working, but the screen backlight remained troublesome. I added "acpi_backlight=vendor apci_osi=Linux" to my kernel command line in /etc/default/grub (and called update-grub and rebooted). I also patched /etc/X11/xorg.conf to include the line
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Option "RegistryDwords" "EnableBrightnessControl=1"
in the section "Device".
With all the options above, backlight control still wasn't working. I tried installing samsung-backlight from the PPA, which actually worked, but only once. After rebooting it stopped working, and when I try to sudo modprobe it, it says "no such device". Adding the "force" parameter does no good either.
I am able to control the backlight via the command line tool xbacklight, and I wanted to use this potential to enable the FN keys manually. I edited ~/xbindkeysrc and added the lines
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"xbacklight -inc 20"
"xbacklight -dec 20"
And it worked! Well, sometimes it works and sometimes it doesn't. After I reboot my PC, I am consistently able to alter the backlight settings via the FN keys. However, sometimes (maybe after going to the standby mode several times? Or is it related to plugging the AC adapter in and out several times?) the system breaks and I can no longer use xbacklight to control the screen brightness. I then have to reboot.
How can I tell what is causing this random behaviour?
I use the proprietary Radeon catalyst driver
to switch between the integrated Intel HD Graphics 3000 and the dedicated Radeon 6490M. These issues appear with both the Intel GPU and the AMD GPU.