Comment 92 for bug 43572

Vyas,
you can check if you have the dcdbas kernel module loaded by issuing: 'sudo lsmod | grep dcdbas' in a terminal without the ticks.
To load the dcdbas kernel module, issue 'sudo modprobe dcdbas'
You might need to restart hal after loading the kernel module to get the backlight working.
This can be done by typing 'sudo /etc/init.d/hal restart'