Ubuntu – Brightness function keys not working

12.10brightnessfunction keyslaptop

I have an ASUS X55A-SPD0204O laptop. The rest of the FN+Fx (where x = number) like sound + – mute, screen turn off, wireless etc. work perfectly.

The problem is with the 2 brightness keys. They just won't work. Any suggestions?

Best Answer

Try adding acpi_backlight=vendor as a boot option. To do that, open a terminal window, and run

gksu gedit /etc/default/grub

Locate this line: GRUB_CMDLINE_LINUX="".

Edit it to look like this: GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

Save the file, then, in a terminal, run sudo update-grub.

Reboot, and check if the brightness keys work.

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Ubuntu – Every function key on laptop works except for brightness

According to the Zenbook Prime community page, the answer is "yes", with a caveat. It looks like the problem will be fixed in a 3.7.x version of the kernel (see this bug), but still exists in 3.5.x (i.e. Ubuntu 12.10).

For now, you can try applying this patch to the 3.5.x kernel. For instructions on building the kernel and applying patches, see here. Again, according to the Zenbook Prime community page the patch is imperfect. The brightness-down key works fine, but the brightness-up key imposes an ~2 second delay before other hotkey presses are registered.

The community page also lists a couple of workarounds that involve the xrandr command. The second workaround involves a custom script that is then mapped to Ctrl+Shift+F5/F6. You could, of course change the keymapping to anything you like (say just F5 or just F6, for example).

Ubuntu – Asus UX303LAB brightness keys do not work

The issue with the touchpad is caused by the trusty and utopic kernels not fully supporting it. Full support for that touchpad is available in kernel 4.0+ so I would recommend downloading and installing the latest stable kernel (currently 4.0.3) onto your system and testing it out, it works flawlessly on my UX303LAB laptop.

mkdir /tmp/kernel-mainline_4.0.3
cd /tmp/kernel-mainline_4.0.3

wget \
    http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.0.3-wily/linux-headers-4.0.3-040003-generic_4.0.3-040003.201505131441_amd64.deb \
    http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.0.3-wily/linux-headers-4.0.3-040003_4.0.3-040003.201505131441_all.deb \
    http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.0.3-wily/linux-image-4.0.3-040003-generic_4.0.3-040003.201505131441_amd64.deb

sudo dpkg -i /tmp/kernel-mainline_4.0.3/linux*4.0.3*.deb

Best Answer

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Ubuntu – Every function key on laptop works except for brightness

Ubuntu – Asus UX303LAB brightness keys do not work

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