I think this issue has been affecting me for a few years now but I just recently started to look into it.
My current system is Ubuntu 19.04 but this issue was present even when I was using 18.04 and 18.10 and even before that. OS: Ubuntu 19.04 CPU: Intel Core i7 6700 Graphics (integrated only): HD Graphics 530 (Skylake GT2) Anyway, from time to time only one of my monitors turn on. When that happens `dmesg | grep i915` prints this: ``` ➜ ~ dmesg -e | grep i915 [ +0.000545] i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=io+mem [ +0.000627] [drm] Finished loading DMC firmware i915/skl_dmc_ver1_27.bin (v1.27) [ +0.003052] [drm] Initialized i915 1.6.0 20181204 for 0000:00:02.0 on minor 0 [ +0.000036] snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915]) [ +0.000047] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device [ +0.249846] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun ➜ ~ dmesg -T | grep i915 [Sat Apr 27 17:47:08 2019] i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=io+mem [Sat Apr 27 17:47:08 2019] [drm] Finished loading DMC firmware i915/skl_dmc_ver1_27.bin (v1.27) [Sat Apr 27 17:47:09 2019] [drm] Initialized i915 1.6.0 20181204 for 0000:00:02.0 on minor 0 [Sat Apr 27 17:47:09 2019] snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915]) [Sat Apr 27 17:47:09 2019] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device [Sat Apr 27 17:47:09 2019] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun ``` When I switch to Wayland, sometimes none of my monitors turn on at all. Once when both turned on, I turned off one and tried to turn it back on again, but it went into energy saving mode. Then `dmesg` was showing this: ``` ➜ ~ dmesg -T | grep i915 [Sat Apr 27 18:14:17 2019] i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=io+mem [Sat Apr 27 18:14:17 2019] [drm] Finished loading DMC firmware i915/skl_dmc_ver1_27.bin (v1.27) [Sat Apr 27 18:14:18 2019] [drm] Initialized i915 1.6.0 20181204 for 0000:00:02.0 on minor 0 [Sat Apr 27 18:14:18 2019] snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915]) [Sat Apr 27 18:14:18 2019] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device [Sat Apr 27 18:14:56 2019] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun ➜ ~ dmesg -e | grep i915 [ +0.000664] i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=io+mem [ +0.000861] [drm] Finished loading DMC firmware i915/skl_dmc_ver1_27.bin (v1.27) [ +0.016298] [drm] Initialized i915 1.6.0 20181204 for 0000:00:02.0 on minor 0 [ +0.000047] snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915]) [ +0.000047] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device [ +23.689059] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun ``` I have attached the complete dmesg output in case that might help. ** Attachment added: "dmesg.txt" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1550779/+attachment/5259448/+files/dmesg.txt -- 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: [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/linux/+bug/1550779/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
