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I recently upgraded from xubuntu 14.04 to 14.10 and then to 15.04 on Lenovo z580. I used to control brightness on 14.04 using xbacklight from command line. Now its not working. 15.04 also has a brightness control option in power management plugin. This one also not working. How to troubleshoot this problem?

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  • by control brightness, do you mean automatic brightness level on AC and Battery?
    – wedu
    Apr 29, 2015 at 17:37

1 Answer 1

Reset to default
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I had the same problem in Ubuntu 15.04. This is how I solved it. First use ls /sys/class/backlight/ to see which video card is installed. In my case the above command showed intel_backlight. After this I did:

sudo touch /usr/share/X11/xorg.conf.d/20-intel.conf # create 20-intel.conf file`

sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf #open the file

and add the following lines to this file 

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

save and exit. Log out and log-in back.

Try the following if the above did not work:

sudo nano /etc/default/grub

Make the line that say GRUB_CMDLINE_LINUX="" to look like the following:

GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

Update grub by: sudo update-grub and reboot.

As a final option try this: xrandr --output LVDS1 --brightness 0.8. Play with numbers other than 0.8 and see what happens.

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  • I tried that, but no change.
    – kanatti
    Apr 29, 2015 at 17:57
  • what does ls /sys/class/backlight/ say?
    – Ron
    Apr 29, 2015 at 17:58
  • intel_backlight
    – kanatti
    Apr 29, 2015 at 18:00
  • Can you please tell what does cat /etc/default/grub | grep GRUB_CMDLINE_LINUX= say too.
    – Ron
    Apr 29, 2015 at 18:03
  • GRUB_CMDLINE_LINUX=""
    – kanatti
    Apr 29, 2015 at 18:08

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