Ubuntu 14.04 brightness problem (Lenovo Z500)

My brightness controls weren't working before, but I didn't really care, but somehow I lowered my screen brightness while downloading league through playonlinux. Now the brightness controls aren't working with the FN keys or in the settings, and its stuck on very low.

I tried this , and everything here , but they didn't do anything.

I am on a Lenovo Z500 using Intel graphics. I have a Nvidia GeForce GT 635M but don't use it.

I have noticed that there are the folders ideapad, intel_backlight and thinkpad_screen in /sys/class/backlight/, each with the files actual_brightness, brightness, and max_brightness. Only in intel_backlight is actual_brightness set to the maximum value. It says, though, that I don't have the permissions to change them with sudo.

Workaround: I got brightness back up by using the brightness FN keys outside of Ubuntu (before it starts or in the BIOS settings), but still whenever I press either of the brightness buttons it goes really dim and cannot be changed.

2 Answers

Two years ago I bought this laptop which works pretty well with Linux. When I upgraded to my new distro, Elementary OS Freya, I noticed the problem that backlight was unable to change. I could change it only on grub screen. After trying every guide on the internet I partially solved the issue by downgrading the kernel (and the related Intel graphics driver) to version 3.13. Yesterday I gave another try. It was very lucky :)

Here the solution:

On the grub configuration file /etc/default/grub modify the following line:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

by adding this string: acpi_backlight=vendor.

In my case it is:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

Update grub by launching:

sudo update-grub

Then create a xorg configuration file like this:

/usr/share/X11/xorg.conf.d/80-backlight.conf

and copy in it this text:

Section "Device" Identifier "Intel Graphics" Driver "intel" Option "AccelMethod" "sna" Option "Backlight" "ideapad" BusID "PCI:0:2:0"
EndSection

Save the file, Reboot, Enjoy :-)

This trick could work on other Lenovo Ideapad laptops. I tested on Lenovo Ideapad z500 on Elementary OS Freya and Debian 8 Jessie.

If you have complitely another laptop you can try this way: Modify grub like in the first part of the guide, update grub, reboot, then verify what backlight "drivers" (I don't know what they are) are being listed. Give:

ls /sys/class/backlight/

and if it gives:

backlight_driver1
backlight_driver2
backlight_driver3

Then create the xorg file with one of the drivers in the list:

Section "Device" Identifier "Intel Graphics" Driver "intel" Option "AccelMethod" "sna" Option "Backlight" "backlight_driver1" BusID "PCI:0:2:0"
EndSection

And reboot. If it works, enjoy, otherwise modify the file with another one in the list the same way.

You could try this