Kernel 5.16: film grain and unregular black screen with USB-C dock


while Kernel 5.16 was still an rc I testet it due to FUTEX(2).
And I noticed a little film grain on the desktop, which was annoying, but okish.
But it got way worse, when playing games. And in an unregular interval both monitors, but just one at a time, showed just a black screen for a few seconds. I even got some small crackle noises. They are connected with a Lenovo USB-C dock (without DisplayLink) to my laptop. So I put 5.15 back in charge again and everything worked flawlessly. 5.16 was still a rc.
Now I am running 5.16.2 and still having the problem. When I switch back to 5.15, everything works again.

This happens only while using the dock.
I do not see any film grain or hear crackle noises while my system is booting, so before the OS is loaded.

  • so, is this a known problem?
  • which output of which commands do you need?
  • is your way shorter to the Kernel devs?
  • do you even need a photo?

Best regards


I do have this film grain as well on 5.15, but way, way less.
I noticed, but I am not 100% sure yet, that if I restart my laptop with 5.15 after I docked it to my USB-C docking station, I have no issues.
This does not help with 5.16, I have the film grain already in the log-in screen.

Lenovo USB-C docking station with latest firmware.

This topic was automatically closed 2 days after the last reply. New replies are no longer allowed.