Comment 33 for bug 1723619

As discovered when testing the latest release of Ubuntu with (mainline) trees, commit 13a86519202c5d119d83640d6f781f3181205d2c seems to introduce a regression when booting with a screen attached to displayport (the system otherwise boots fine with the same kernel using an HDMI output).

An original bug was filed with the Ubuntu bug tracker and contains information about bissection: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1723619

A (set of) dmesg outputs can be found here: https://pastebin.ubuntu.com/25767385/

4.14-rc5 still exhibits this behavior on the tested system.

Please don't hesitate to reach out to me should you need more information - one affected system happens to be my main workstation.