I tried to boot to linux-image-4.4.0-62-generic but I could not get past the login screen. So I reinstalled the linux-image-4.4.0-62-generic and run update-grub. Then I could boot to it (linux-image-4.4.0-62-generic) and the brightness is working again. I think it is a kernel regression.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1667323 Title: Backlight control does not work and there are no entries in /sys/class/backlight To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1667323/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
