Reading this bug-report the issue seems to be that dell-uart-backlight is non-functional in the 6.5.y kernels and completely missing in the 24.04 6.8.y kernels. While in Ubuntu 23.04 with its 6.2 kernel dell- uart-backlight is present and functional.
The problem is that Canonical / Ubuntu wrote the original dell-uart- backlight driver but the way it accessed the serial port was rather hacky so it was never accepted upstream and it seems that when rebasing to a new kernel Ubuntu dropped their downstream patch (after it broken in 6.5.y ?). After I received the first bug reports about backlight issues on Dell AIO systems a few months ago I have re-written the dell-uart-backlight driver and submitted it upstream, this new rewrite was accepted upstream in kernel 6.10 . So I expect that backlight control will start working again for you if you upgrade to kernel 6.10 or newer. I'm not an Ubuntu user myself, but there are unmodified mainline kernels available for Ubuntu which allow you to update to 6.10.y without waiting for Ubuntu to move to this kernel version. Here are some docs on this: https://itsfoss.com/upgrade-linux-kernel-ubuntu/ https://wiki.ubuntu.com/Kernel/MainlineBuilds -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2067498 Title: Can't control display backlight in 24.04 on Dell AIO system To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2067498/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
