Toshiba Satellite U940-101 keyboard backlight does not work

[Staedie]

As the subject says, I have a Toshiba Satellite U940-101 and my keyboard backlight does not work with Linux. I am using Linux Mint 14 Cinnamon 64bit. On my laptop, Windows 8 was pre-installed and I can start Linux only by switching off the UEFI option and the secure boot option in Bios. The backlight works while I am in the Bios (version 1.30) and in Windows, but it turns off as soon as I boot Linux, just after the Toshiba booting symbol disappears.

In other forums I have read that switching off ACPI in Bios could help in making the backlights work in Linux, but apart from the fact that this would turn off other important functions, my Bios does not even provide the option of turning on/off ACPI.

I have already tried another Linux distro (Fedora 17), but there I have the same issue with the backlights. I have also installed all the drivers I could find for my Toshiba Satellite, both from the Toshiba website and the Linux (Mint) compatibility drivers from the software manager.

Could it be a kernel problem which is not solved / updateable yet?

I am a beginner in Linux and would be thankful for every hint.

[linucksrox]

I wonder if it's the same issue I recently had with my Acer laptop. I added acpi_backlight=vendor to the grub entry which allowed the backlight hotkeys to function properly. Follow the steps in this post to see if that helps you. Don't forget (like I did) to run sudo update-grub to actually write the changes to the bootloader after editing /etc/default/grub.

[Staedie]

Thanks for your reply!

What I actually meant was not the function on the keyboard to regulate the backlight of the screen, but the lights of the keyboard itself, the small lights under each keyboard button. These don't work. By pressing "FN + Y", the combination with which I normally can turn on/off those lights, there appears a symbol on the screen for one second that refers clearly to this function, as if I really could turn the lights on or off, but it doesn't change anything on the concrete keyboard backlights themselves. They stay off. So I don't know.

Does anybody else have any ideas?

[raficulous]

Hi! Sorry I'm late, this is my first post on this forum

Try this: install kernel 3.9.3 and then shut down your laptop. From the bios settings set the keyboard light mode in ON or TIMER as you prefer. Than boot with 3.9.3 and you should have your kbrd backlight back again. After this you can shut down the laptop and boot it again with the kernel you prefer, it should mantain the service active. EVERYTIME you unplug the current (by removing the battery and the wire) you'll have to boot with 3.9.3 again in order to restore the backlight mode, but always just for the first time. I hope it could help someone!

*tested on mint 17 cinnamon 64bit toshiba U940-103*