1. Update BIOS firmware to version 1.09. (download from Acer web site and install in Windows)
2. Edit /etc/default/grub file and add: acpi_osi=Linux acpi_backlight=vendor
For example:
$ sudo gedit /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"
3. Update grub:
$ sudo update-grub
Now arrows keys change brightness are working, but screen brightness applet does not show up. And brightness is not automatically adjusted when power cord has been unplugged. If you find a better solution let me know.
Acer Aspire 4740 (Ubuntu Linux 2.6.32-24) Solved:
1. Update BIOS firmware to version 1.09. (download from Acer web site and install in Windows)
acpi_ osi=Linux acpi_backlight= vendor
GRUB_ CMDLINE_ LINUX_DEFAULT= "quiet splash acpi_osi=Linux acpi_backlight= vendor"
2. Edit /etc/default/grub file and add:
For example:
$ sudo gedit /etc/default/grub
3. Update grub:
$ sudo update-grub
Now arrows keys change brightness are working, but screen brightness applet does not show up. And brightness is not automatically adjusted when power cord has been unplugged. If you find a better solution let me know.
Kind regards.