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I'm running a fresh install of Kubuntu 20.04. Many times when I shutdown (not every time, but often), it pauses for a minute or so before showing the error:

 [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun

This is usually associated with screen flickers. The screen also sometimes flickers during normal usage. Googling has yielded MANY reports of similar issues, but the given solution always seems to be "update your kernel" or to use a workaround that's deprecated (because it was for an older kernel). Example: drm/i915: Resetting chip after gpu hang

I'm currently on kernel 5.4.42. I've also tried 5.4.0.29 (since 5.4.0 is what originally shipped with Kubuntu) and 5.6.14 (the latest stable). All have the same issue.

I've tried updating drivers via

sudo ubuntu-drivers autoinstall

but the behavior is the same.

AdminBee
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J23
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2 Answers2

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I was able to prevent this from happening by disabling C-States in my laptop's firmware configuration ("BIOS"). For reference, it's a Dell Latitude 5490.

Found the solution here: https://askubuntu.com/questions/895329/flickering-screen-cpu-pipe-b-fifo-underrun-when-i-use-the-termnal

J23
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You can look here: https://askubuntu.com/questions/1272268/ubuntu-20-04-continious-screen-flicker-after-return-from-supend-error-cpu

I solved it with a lower self created resolution: 1912x1080.

I would like to know: Are you suffered from screen tearing too?

Arno
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  • No screen tearing, & per above, this was solved w/o having to lower the resolution (via a BIOS setting). – J23 Sep 29 '20 at 17:06
  • You might decide what is more important: loose 8 pixel or 2hours battery run time. Best would be Linux team would fix the issue ;) – Arno Sep 30 '20 at 16:12
  • Ohhh, does that actually have a major impact on battery life? I seem to recall reading it was very negligible. Do u have some contrary info about that? – J23 Oct 01 '20 at 03:06