Found one easy solution (a least on Ubuntu 20.04) to implement manually solution by changing grub configuration.
Edit /etc/default/grub To the parameter GRUB_CMDLINE_LINUX_DEFAULT add "acpi_backlight=vendor" The line should be GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor" update grub sudo update-grub reboot Don't know how to implement this in ubuntu distribution. Is it possible to create specific grub config during the installation process ? -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to gnome-power-manager in Ubuntu. https://bugs.launchpad.net/bugs/818826 Title: backlight brightness control won't work in 2011 iMac 27" Status in gnome-power-manager package in Ubuntu: Confirmed Bug description: When I press the 'Brightness Control(UP, DOWN)' key in Apple Keyboard, the OSD shows Increasing Backlight(or Decrease) at the right-top corner. But the Screen Brightness doesn't changed. Also, I waited 15 minutes, the screen turned black. (Power Setting) But the Backlight still alive. This iMac has AMD Radeon HD 6970M. I think maybe it's because the driver doesn't exist in kernel module. Sorry about my poor English and few information. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-power-manager/+bug/818826/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
