Just to say that I have exactly the same symptoms. After upgrade to 14.04 (kubuntu in my case) my external monitors become very unstable. My laptop is a DELL XPS 13, and I user a DELL Mini Display Port to VGA.
I have the same errors in dmesg "pipe B stuck" but also the "too many retries, giving up" mentioned in https://bugs.freedesktop.org/show_bug.cgi?id=56834 It happens with my regular external monitor (very often when the screen goes to sleep after inactivity, it won't wake up), but also when I connect to external videoprojectors (and sometimes even more dramatically: the computer freeze) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1314213 Title: [Lenovo ThinkPad X220] External DP1 monitor extremely unstable since upgrade to 14.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1314213/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
