I upgraded to 5.4.0-18-generic and the problem is now fixed. Both screen backlight and keyboard backlight controls are now working as expected.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1862835 Title: [Dell XPS 15 9570] Unable to change laptop screen brightness or keyboard backlighting To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1862835/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
