Laptop keyboard backligt on Toshiba X775-3DV78

Question

I have installed “Linux Mint 18.1 Serena” on my Toshiba laptop (X775-3DV78) and have been using it for a while. And I love it.

I’ve always wanted to switch to Linux, from Microsoft. It is unbelievable how much Linux has grown and matured up.

Everything works well with Linux Mint other than the keyboard backlight on my laptop.

I do most of my typing under dim or no light at night. So, the keyboard backlight on my Toshiba laptop is not just a fancy feature because it looks cool, but it is a feature I really need. Unfortunately, I can’t get the laptop keyboard-backlight to work on Linux Mint no matter how much research I’ve done in Google.

Is there a way to turn on the keyboard backlight on my Toshiba laptop?

Thank you... Thank you... Thank you...

Answer 1

I am only writing this as a reply because I don't have enough rep points to add a simple comment.

Could you post the output of the following command when typed into the terminal?

grep "GRUB_CMDLINE_LINUX" /etc/default/grub

Also, post the output of:

which acpi

Also, what kernel version are you using?

Update:

Since the user has supplied the output of the above commands, I'll update this instead of writing a new reply.

Try this first:

sudo gedit /etc/default/grub, then type the password for the administrator. Go to the line that says, 'GRUB_CMDLINE_LINUX=quiet splash' and change that line to read 'GRUB_CMDLINE_LINUX= quiet splash acpi_backlight=vendor' then save the file. Then, type sudo update-grub. Reboot.

After reboot, try the function keys for your keyboard. I think this may be fnc-z. Whatever the keyboard backlight buttons are, try them. If it does not work, then backup and undo all the changes you made to the /etc/default/grub file.

The idea behind this is that perhaps the fnc keys for your keyboard isn't working.

Should this method not work, does the keyboard come on at all before the system starts to boot linux?

You mentioned in the comments that you tried to echo 1 to one of the devices. We may not have the correct path. Post the output of the following command:

find /sys/ -iname 'backli'

---

It could very well be a linux kernel issue. The linux 4.4ish may not have proper support for the keyboard. You may wish to install the newest kernel...but keep in mind, this could cause other issues. Also, try this at your own risk. You may wish to read about the risks involved in updating the kernel before trying this. If you decide to give it a shot, then follow these instructions:

Updating to Linux Kernel 4.13-r1 for Linux Mint (or Ubuntu):

cd /tmp sudo wget linux-headers-4.13.0-041300rc1_4.13.0-041300rc1.201707151931_all.deb

sudo wget linux-headers-4.13.0-041300rc1-generic_4.13.0-041300rc1.201707151931_amd64.deb

sudo wget linux-image-4.13.0-041300rc1-generic_4.13.0-041300rc1.201707151931_amd64.deb

sudo dpkg -i *.deb sudo upgrade-grub

Then reboot, and make sure to choose the new kernel in GRUB. Once booted, make sure that you've booted with the newest kernel by issuing:

uname -r

Ensure that version 4.13.0 is listed. If not, then you did not choose the correct kernel within GRUB.

Sometimes updating the kernel will cause other issues and can lead to undesired regressions. Should this happen, then delete the newly installed kernel. To do this issue:

sudo apt purge linux-image-4.13.0-* sudo update-grub

Update:

With the additional information regarding the problem provided in the comments, try this:

Change the line "GRUB_CMDLINE_LINUX" to GRUB_CMDLINE_LINUX="i8042.reset"

If the above doesn't work, then try: GRUB_CMDLINE_LINUX="i8042.reset i8042.nomux=1"

Also, remember to do "sudo update-grub" after any change to the /etc/default/grub file.

NOTE: You may wish to add the "quiet splash" to the line also. Just boot with and without and determine if you do or not.

Try this and report back. If it does work, I'll explain why it did afterwards.