Also, if the "Enable Switchable Graphics" option in BIOS is set to true, the brightness control would work.
This option will make two more backlight interface available.
ubuntu@201305-13527:~$ ls /sys/class/backlight/
acpi_video0 acpi_video1 intel_backlight
Also, if the "Enable Switchable Graphics" option in BIOS is set to true, the brightness control would work. 201305- 13527:~ $ ls /sys/class/ backlight/
This option will make two more backlight interface available.
ubuntu@
acpi_video0 acpi_video1 intel_backlight