Perhaps this comment from the changes log is relevant: amd/display: set backlight only if required
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-hwe-5.15 in Ubuntu. https://bugs.launchpad.net/bugs/1981727 Title: kernel 5.15.0-41 update results in dim screen (5.13.0-52 OK) Status in linux-hwe-5.15 package in Ubuntu: New Bug description: A recent update to 5.15.0-41 results in my laptop screen (Dell Precision 7520) being unable to come up to full brightness. I have verified that I can revert to 5.13.0-52 and the problem is not there. I looked at /sys/class/backlight/nv_backlight/max_brightness which lists 1023 in the newer kernel and 100 in the older one. I have verified that changing the brightness manually does change /sys/class/backlight/nv_backlight/brightness, all the way up to 1023, but it's just not enough... the screen is still very dim. The other screen (standalone monitor through docking station) on a two-headed display is fine. I tried to write 100 into max_brightness but of course, the "file" is read-only. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-hwe-5.15/+bug/1981727/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
