When i just try adjusting brightness, the indicator changes but the screen does not change brightness. I have tried adding acpi_backlight=vendor to my grub file and also doing

echo x > sudo tee /sys/class/backlight/dell_backlight/brightness


echo x > sudo tee /sys/class/backlight/intel_backlight/brightness

Brightness used to change fine but now is not working on a new ubuntu install. I am using a dell xps 14 with a NVIDIA 630M using the nvidia-340-updates driver & nvidia prime. Also supports ivybridge graphics but I am using the 630m. Thanks in advance

creating /X11/xorg.conf.d/20-intel.conf did not fix my issue.
Model is Dell XPS 14-l421x
kernal version 3.16.0-45-generic
Updating to kernal 3.19.0-25-generic and ubuntu 15.04 did not fix my issues
The problem was the bios setting "Load legacy option rom" being set to Enabled, setting this to disabled fixed my backlight.

  • What is your laptop model?
    – Pilot6
    Aug 7, 2015 at 12:44

2 Answers 2


i can recommend you to upgrade to newer kernel, or you can try to create file /usr/share/X11/xorg.conf.d/20-intel.conf with this code in it:

Section "Device"
        Identifier  "card0"
        Driver      "intel"
        Option      "Backlight"  "intel_backlight"
        BusID       "PCI:0:2:0"
  • creating the file did not change anything.
    – Noctane
    Aug 7, 2015 at 12:44
  • you should create it with root permissions and you must reboot your PC after that. Anyway that worked for me on my Acer laptop which was with i believe 3.12 kernel, but after i updated kernel to newer version issue gone completely. What kernel ver. do you use? Type uname -r in terminal and post output. Aug 7, 2015 at 15:23
  • I tried again and still nothing, file was definitely created as root. my kernal is version 3.16.0-45-generic
    – Noctane
    Aug 8, 2015 at 3:37
  • As i said before, i can only recommend you to install newer kernel. Because 20-intel.conf and acpi_backlight=vendor solutions don't work for you, which is strange. Aug 8, 2015 at 10:44
  • Updating to 3.19.0-25-generic as well as ubuntu 15.04 did not fix my issue. turned out to be a BIOS settings problem.
    – Noctane
    Aug 14, 2015 at 4:02

I Fixed my problem. The solution for me was enabling "Load legacy option rom" in the BIOS.

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