I tested the issue with Ubuntu kernel 7.0.0-31 on my Dell Inspiron 5480. The problem was caused by the "acpi_backlight=video" kernel parameter that I had previously added while troubleshooting the issue.
With "acpi_backlight=video" enabled, the system exposed "acpi_video0" and "acpi_video1". "brightnessctl" was able to control "acpi_video1" and physically change the panel brightness, but the GNOME brightness slider was controlling "acpi_video0", which did not change the actual panel brightness. I removed "acpi_backlight=video" from the kernel command line, ran "update-grub", and rebooted. After that, the Ubuntu/GNOME brightness slider works correctly. So, at this point, the brightness issue is resolved on my system with kernel 7.0.0-31 without the "acpi_backlight=video" parameter. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2162937 Title: Backlight brightness cannot be changed from OS on Dell Inspiron 5480 (WQBC WMI firmware bug) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2162937/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
