Public bug reported: On Kubuntu 15.10, KDE Framework 5.18.0, Qt 5.5.1, kernel 4.4.1-040401-generic from http://kernel.ubuntu.com/~kernel-ppa/mainline/ (I upgraded hoping it would solve the problem, but it did not). Haswell i7-4771 with integrated GPU (no other graphics card). 3-monitor setup.
Several times a day the display seems to crash in various ways, some recoverable (e.g. by restarting plasmashell or sddm) but sometimes a monitor stays blank, corrupt or unresponsive and only a full reboot helps. I also see a plasma crash dialog every time I return to my desktop after the screens went into power-savings mode when I was away (I don't know if this is related or a plasma bug). It also happens sometimes while dragging a windows (desktop effects are on), while watching a video (I now get occasionally a few seconds with black output in the middle of the video too). It's hard to pinpoint which components are unstable, likely more than one, but this is a starting point since I get the following message in dmesg which I assume is at a lower level than the desktop environment (correct me if I'm wrong): [Thu Feb 4 10:44:20 2016] [drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR* uncleared fifo underrun on pipe A [Thu Feb 4 10:44:20 2016] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun ** Affects: xserver-xorg-video-intel (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1541751 Title: [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1541751/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs