Description of problem:
After upgrading the kernel from 4.15.15-300.fc27 to 4.16.4-200.fc27, the screen (both internal or hdmi external) exhibits important flickering. Everything is fine with kernel 4.15.15.
Steps to Reproduce:
1. boot kernel version 4.16.4-200.fc27
2. login to wayland
The screen flickers
GPU : Intel HD Graphics 620 (Kaby Lake GT2)
CPU : Core i7-7500U
I've been running with i915.enable_rc6=0 for the last few month, and the flickering looks similar to the one present when running with RC6 enabled. Enabling/disabling RC6 on the 4.16.4 kernel does not change the behaviour.
Thanks for the report, I'm moving this to the Intel driver component since we track graphics related problems there. Some first steps for debugging would be to check whether this is present in the Rawhide kernel. If it is, bisecting would be very helpful.
I'll try the rawhide kernel and report back here. I'm not sure what you mean by "bisecting", but I'll do what I can to help.
Ah, excellent, I've been looking for someone to walk through the guide on bisecting!
Documentation on how to bisect the kernel is at https://docs.fedoraproject.org/quick-docs/en-US/kernel/troubleshooting.html#bisecting-the-kernel. If anything isn't clear, or you get stuck for some reason, please let me know.
In https://bugzilla.redhat.com/show_bug.cgi?id=1573482 Laura notes i915.enable_rc6 was removed intentionally so I'm guessing that's the root cause of your issue. It would be best to report this upstream to bugzilla.freedesktop.org (or add to the report from Klaus if they file a bug), then link it back to #1573482.
*** This bug has been marked as a duplicate of bug 1573482 ***