I didn't have time to check this, but from what you described. If there are 2 acpi_video in /sys/class/backlight, that means BIOS provides us 2 ACPI backlight devices. But only one of them is the right one to adjust the brightness.
If the above guess is correct, then the 2 acpi backlight device should be /sys/class/backlight/acpi_video0 and /sys/class/backlight/acpi_video1 The working one should be acpi_video0, and acpi_video1 is the redundant one. You can check it by echo value to the "brightness" file in those directory to figure out which one is working. So, the problem is why gnome-setting-daemons choose to use acpi_video1 to adjust the brightness instead of acpi_video0. More over, I think, in this case, g-s-d should try to adjust all acpi backlight devices if there are more than one device exists. So, it's a BIOS issue or a g-s-d issue, not kernel. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1169409 Title: [HP Pavilion 23] Brightness control doesn't work. To manage notifications about this bug go to: https://bugs.launchpad.net/hwe-next/+bug/1169409/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
