I think the status of this this bug should be set to "fix released". The linked freedesktop bug report was already set to status "resolved fixed" and I was able to setup DisplayPort MST with a Dell U2515H and an older U2312HM on my Haswell desktop running 14.04.4.
** Changed in: xserver-xorg-video-intel (Ubuntu) Status: Confirmed => Fix Released -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1104230 Title: DisplayPort 1.2 MST support is missing in the Intel driver To manage notifications about this bug go to: https://bugs.launchpad.net/xserver-xorg-video-intel/+bug/1104230/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs