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I am unable to reduce Laptop brightness in Ubuntu 20.04 after upgrading.

  1. Installed brightness-controller to adjust brightness but still unable to adjust the brightness.

    sudo add-apt-repository ppa:apandada1/brightness-controller sudo apt update sudo apt install brightness-controller

  2. Tried to solve issue by enabling Laptop Specific Drivers by adding below line in /etc/default/grub

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

But still unable reduce brightness.

sudo lspci|grep VGA
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (Whiskey Lake) (rev 02)

sudo lshw -c video
*-display UNCLAIMED

   description: VGA compatible controller
   product: UHD Graphics 620 (Whiskey Lake)
   vendor: Intel Corporation
   physical id: 2
   bus info: pci@0000:00:02.0
   version: 02
   width: 64 bits
   clock: 33MHz
   capabilities: pciexpress msi pm vga_controller bus_master cap_list
   configuration: latency=0
   resources: memory:c0000000-c0ffffff memory:b0000000-bfffffff ioport:4000(size=64) memory:c0000-dffff
singrium
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Sreeraju V
  • 161
  • Does it not work using the designated hotkeys? Maybe post the full sudo lshw -c video. Probably you will be using the kernelmodedriver i951. Also, revert you changes if they do not work. – vanadium Jun 22 '20 at 10:37
  • Updated Question with "sudo lshw -c video" output – Sreeraju V Jun 22 '20 at 11:08
  • I've had the same issue, it was solved. try this https://askubuntu.com/questions/1230937/ubuntu-20-04-brightness-adjust-not-working – Giorgos Saridakis Jun 22 '20 at 17:58
  • Getting error xrandr -q | grep " connected" xrandr: Failed to get size of gamma for output default default connected primary 1920x1080+0+0 0mm x 0mm – Sreeraju V Jun 24 '20 at 09:21

1 Answers1

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I had the same problem as you and the only solution that worked for me was to upgrade the kernel as per the procedure is described in this video: https://www.youtube.com/watch?v=PgRgUe3eWj0. However, I will post the steps here in case the link goes offline. However, this should be a last resort in case nothing else works. Make sure Secure Boot is turned off in the BIOS. Make a backup of your data before this.

Step 1: Add Cappelikan PPA

To do this, fire up a terminal and type:

sudo add-apt-repository ppa:cappelikan/ppa

Step 2: Make sure system is up to date and install Mainline

The Cappelikan PPA has Mainline in its repository, which is a reliable application for upgrading the kernel in Ubuntu.

To install Mainline and make sure the system is up to date, type this in the terminal one after another:

sudo apt update

sudo apt install mainline

Step 3: Upgrade kernel

Open up Mainline through the application menu. It should appear as 'Ubuntu Mainline Kernel Installer' (you may not see the full name, it might appear as 'Ubuntu Main...' or something along those lines)

Wait for the application to load, and it should show you a list of kernels to install. I suggest you go with a kernel that is 5.8 or above. Anyway, select a kernel and click 'Install'. The process will take some time.

Once its done, it'll tell you to close the window and restart.

Reboot and run uname -r in the terminal to check your kernel version. If it is the one you selected and installed earlier, you should be good to go and your brightness problem should be fixed.

Wish you best of luck. If you any more problems, don't hesitate to ask.

Vishal Bagadi
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