SKL: Display flickering - *ERROR* CPU pipe A FIFO underrun

I am creating the bug on-behalf of the user based on the email I received.

My laptop (core m5-6y54) starts flickering after returning from Suspend (to RAM) or other commands touching the video driver (xrandr, powertop --calibrate, ...)

From kernel (tested with up to 5.7) I get the message: [drm:intel_cpu_fifo_underrun_irq_handler [i915]] ERROR CPU pipe A FIFO underrun

I added a bug with more details here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1872760 but guys from Ubuntu seems not able to help (as it is an upstream bug) !?

This happend not in older kernels, but these have the problem not to go in power save states. So I think the fix of that https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1863489 causes this regression.

Hope someone can help. For a laptop it is better to have both - standby and power saving. Thank you. Arno