I tested both 4.8.17 and 4.9.6 mainline kernel, shutdown/reboot both works fine there. However 4.8.0-34-generic Ubuntu kernel still has the problem.
** Tags added: kernel-fixed-upstream -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1659623 Title: Shutdown/reboot hang on Dell XPS 15 9550 BIOS 1.2.18+ To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1659623/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
