I see the problem on my Thinkpad T450 when I connect external display on 16.04 LTS with Linux kernel 4.13.0-26-generic:
dmesg -T | grep i915 [Thu Jan 18 15:24:30 2018] i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=io+mem [Thu Jan 18 15:24:30 2018] [drm] Initialized i915 1.6.0 20170619 for 0000:00:02.0 on minor 0 [Thu Jan 18 15:24:31 2018] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device [Thu Jan 18 15:24:37 2018] snd_hda_intel 0000:00:03.0: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915]) [Thu Jan 18 16:05:48 2018] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun [Thu Jan 18 16:07:26 2018] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun [Thu Jan 18 16:29:20 2018] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun [Thu Jan 18 16:29:22 2018] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun [Thu Jan 18 16:29:56 2018] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun [Thu Jan 18 16:31:29 2018] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun [Thu Jan 18 16:31:37 2018] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun [Thu Jan 18 16:35:19 2018] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun Not sure what's the workaround. I don't see the problem when I use laptop's display. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1550779 Title: [i915]] *ERROR* CPU pipe A FIFO underrun - Xorg glitches To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1550779/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
