[bisected, patch attached] [drm] [i915] Flickering on build-in display since kernel v4.1 (HP Elitebook Folio 1040 G1)

Basically this is a duplicate of issue #306 (closed) with new information. Unfortunately I can't reopen that issue so creating a new one. Sorry about that. Please leave this issue or reopen the old one. Thanks!

The problem occurs with notebook HP Elitebook Folio 1040 G1 which comes with processor Intel i5-4210U.

I have a few types of periodic flickering:

1. If I leave mouse cursor for a few seconds, then start moving it, there's slight flicker (like display brightness changes a bit)
2. On the top left corner sometimes appears artifacts. It's relatively easy to see with black window decorations on top of the screen. This one is showed at the attached video bellow

VID_20190526_162622.

Where it's not reproducible:

1. Windows and BIOS
2. With boot option nomodeset
   Boot option like i915.enable_psr=0, i915.enable_rc6=0, intel_idle.max_cstate=4 didn't help. Resolution or refresh rate changes don't make any difference
3. With kernel 4.0.9. Version 4.1-rc3 has this problem. Tested on Ubuntu 16.04

I already tried new kernels (including latest drm-tip version from Ubuntu (2021-05-04 02:47). The problem persists.