Note: This is not a duplicate of Ubuntu 20.04 brightness adjust not working, Cannot change brightness (Ubuntu 16.04 LTS and onward) or Unable to change brightness in settings because the answers do not fix the problem.

On Dell Inspiron 11, Ubuntu 20.10, I enabled the brightness laptop keys and Settings Power panel brightness slider by adding acpi_backlight=vendor acpi_osi=linux to /etc/default/grub based on this post.

Following this post, I installed xbacklight and $ find /sys -type f -name brightness returned:


But I was unable to add a softlink:

$ sudo ln -s /sys/devices/platform/dell-laptop/backlight/dell_backlight/brightness /sys/class/brightness
ln: failed to create symbolic link '/sys/class/brightness': Operation not permitted

I created /etc/X11/xorg.conf with these contents:

Section "Device"
    Identifier  "Device0"
    Driver      "intel"
    Option      "Backlight"  "dell_backlight"

And rebooted, but the brightness does not change when I adjust the slider or use the brightness keys.

What else can I try here?

  • Does this answer your question? Ubuntu 20.04 brightness adjust not working – David Apr 1 at 8:44
  • No, I'm afraid not. Please see the note and link at the top of the post. – koyakun Apr 3 at 4:16
  • It's also worth pointing out that the "question" in that post is extremely vague and none of the proposed solutions in that post are marked as answering the "question." – koyakun Apr 3 at 4:20

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