Dell Inspiron 7580 hybrid laptop has issues with external monitors when on "performance" (dGPU) mode; the external screen will start blinking and dmesg has lots of:
[492.008927] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun
[492.009818] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun
I don't have full logs right now, but at least 4.20 is still affected. Everything newer would need a patched nvidia dkms and that hasn't been tried yet..
when it's running on iGPU everything is fine AIUI
The issue happens to WHL (Whiskey Lake)
00:02:0 VG compatible controller : Intel Corporation Device [8086:3ea0]
Could you disable NV modeset to reproduce issue again and dump i915 log. Thanks,
(In reply to Cooper Chiou from comment #2)
> Could you disable NV modeset to reproduce issue again and dump i915 log.
the issue is still reproducible after removing "nvidia-drm.modeset=1" from kernel parameter.
could you check the logs from the dell system shipped to you? Thank you.
I just received Bucky N5 device, but I can’t reproduce this external display blinking issue with Dell 2K monitor via DP and Sony FHD monitor via HDMI in NV Performance mode and no any FIFO underrun error either.
Please share more detail reproducing steps and record the symptom video to share.
Here is reproducing steps:
1. connect an external monitor via HDMI port
2. switch display mode to mirror mode
3. switch display mode to external only
4. switch display mode to internal only
5. switch display mode to extended mode
6. Go to 2