In Ubuntu 13.10, I found that I was unable to change the brightness either by using the brightness keys or moving the brightness slider in System Settings. To fix the issue, I had to change the file /etc/default/grub to reflect the following:
GRUB_CMDLINE_LINUX=”quiet splash acpi_osi=Linux acpi_backlight=vendor”
[UPDATE]: Ubuntu now supports ATi + Intel hybrid graphics systems in the 13.10 and 12.04.03. Here’s how to make it work:
Make sure any other fglrx driver is not installed. Install fglrx and fglrx-pxpress as follows:
sudo apt-get install fglrx fglrx-pxpress
If you have added the lines in /etc/rc.local as in the previous solution, please remove them and reboot the system.
In my machine the AMD/Intel setup is working fine. There is no high power consumption and overheating of the system. Also, I am able to switch between the cards effortlessly through Catalyst Control Center. Thanks Ubuntu/AMD!
In systems with ATi + Intel hybrid graphics running *Ubuntu 13.04 and 13.10 distros, I have noticed high CPU usage and overheating resulting in very high power consumption and low battery backup.
For people facing the issue, this can be solved by adding the following lines in the /etc/rc.local file:
sudo chmod -R 705 /sys/kernel/debug
sudo chown -R username:username /sys/kernel/debug/vgaswitcheroo
sudo echo OFF > /sys/kernel/debug/vgaswitcheroo/switch
Replace username is the second command with your username.
After this run: sudo update-grub and reboot your system.
This is a temporary fix as here we disable the discrete AMD card and just keep the onboard Intel card switched on.