Cannot adjust brightness after sleep

Question

I have a Toshiba Satellite R830 laptop with Ubuntu 12.04.1 64 bit. The Fn + F6 and Fn + F7 buttons adjust brightness until I put my laptop on sleep.

On wakeup they don't work any longer. Is there a solution or a workaround to this issue?

Solution 1

I found a better solution than the one selected above.

1. Press Alt + F2 and type gksudo gedit /etc/default/grub.
2. Find the line than starts with GRUB_CMDLINE_LINUX_DEFAULT= and modify it as follows: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor".
3. In a terminal (ctrl + alt + T) type sudo update-grub.
4. Reboot.

Problem solved.

More info here: https://wiki.ubuntu.com/Kernel/Debugging/Backlight

Edit

This solution no longer works on 13.10 and 14.04.

A solution that does is creating an xorg configuration file:

1. In a terminal type sudo touch /usr/share/X11/xorg.conf.d/20-intel.conf to create the file.
2. Followed by sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf to edit its content.
3. Then add the following content and save:

Section "Device"
        Identifier  "card0"
        Driver      "intel"
        Option      "Backlight"  "intel_backlight"
        BusID       "PCI:0:2:0"

EndSection

Log out and in again.

Source: Fix Brightness Control Not Working for Ubuntu 13.10 & 14.04

Solution 2

I had the same problem with a Toshiba Portege R935 in 12.04, and I discovered this (not so elegant) workaround:

• as root (not with sudo but actually changing user: su root), change the value in sys/class/backlight/intel_backlight/brightness

  for instance:

  echo 2937 > /sys/class/backlight/intel_backlight/brightness
  

Warning: these values are not between 0 and 7 (as the ones in the other directory), but between 284 and 4539, or something like that.

Comments

[thorstorm]

Do you have to do it every time you need to change the brightness?

[mfiori]

Well, yes, but I guess you can create a shortcut as the proposed solutions in other posts. I haven't do it yet, I'll let you know if I try. At least it's good to know where the problem is...

[Steffan]

You're adding a kernel parameter. Could you post a link, or directly describe why this is needed?

[thorstorm]

See modified answer. Not that I understand the details of it.

[Daniel Jonsson]

The second solution worked for me on Toshiba R830-13D running Fedora 21 Workstation with kernel 3.17.8.

[lechup]

Solution Ubuntu 14.04 also work for Lenovo T400! Thanks!

[Admin]

The first solution worked on an Asus Zenbook with Debian Jessie (kernel 3.16.0), however, I had to remove the backlight part because with that I couldn't change my backlight.