创建文件并写入内容: 
	sudo vi /usr/share/X11/xorg.conf.d/10-nvidia-brightness.conf 
	  
Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "Quadro K1000M"
    Option         "RegistryDwords" "EnableBrightnessControl=1"
EndSection
注销即可
	
	
 
	from:http://askubuntu.com/questions/76081/brightness-not-working-after-installing-nvidia-driver
	
	原文摘要:
	
	
	
	These days X automatically configures itself, so creating an xorg.conf file might make your system inflexible. Instead you can add a section to a file in /usr/share/X11/xorg.conf.d/ and X will include that section in the configuration that it automatically generates.
	So to get the screen brightness keys working with your Nvidia graphics card, create a file in the xorg.conf.d directory, e.g:
sudo gedit /usr/share/X11/xorg.conf.d/10-nvidia-brightness.conf 
	Paste the following into the file:
Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "Quadro K1000M"
    Option         "RegistryDwords" "EnableBrightnessControl=1"
EndSection 
	Log out and log back in, or reboot, and your brightness keys should now work!