I tried 19.10 and 20.04 (daily build) on an AMD platform (AMD Ryzen 5 2500U with Radeon Vega Graphics), and the backlight works without problems.
This platform has the same symptom as described in the bug description - actual_brightness is a fixed and higher value, and it does not change with brightness. The max_brightness is 255 (which is fixed in amdgpu driver) and brightness can be changed from 0 to 255. I built a kernel, based on 5.6rc5, that has actual_brightness = brightness. It is available for testing @ https://people.canonical.com/~alexhung/LP1861925/poc_kernel/ The actual_brightness is read from hardware but it doesn't reflect actual brightness. Only AMD developers can answer why it doesn't work accordingly - perhaps different hardware has different address and this needs updating. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1861925 Title: BrightnessOutofRange: Actual brightness for amdgpu_bl0 not in range 0..255 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1861925/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
