Bug 1573112

Summary:	Screen flickering on Intel HD 620 after upgrade to 4.16.4
Product:	[Fedora] Fedora	Reporter:	Julien <julien+redhatbugzilla>
Component:	xorg-x11-drv-intel	Assignee:	Adam Jackson <ajax>
Status:	CLOSED DUPLICATE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	27	CC:	airlied, ajax, bskeggs, ewk, hdegoede, ichavero, itamar, jarodwilson, jcline, jglisse, john.j5live, jonathan, josef, julien+redhatbugzilla, kernel-maint, linville, mchehab, mjg59, steved, xgl-maint
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Last Closed:	2018-05-01 14:51:53 UTC	Type:	Bug
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Description Julien 2018-04-30 08:24:39 UTC

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.

How reproducible:
Always

Steps to Reproduce:
1. boot kernel version 4.16.4-200.fc27
2. login to wayland

Actual results:
The screen flickers

Expected results:
No flickering

Additional info:

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.

Comment 1 Jeremy Cline 2018-04-30 14:21:45 UTC

Hi Julien,

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.

Comment 2 Julien 2018-04-30 14:29:20 UTC

Thanks Jeremy.

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.

Comment 3 Jeremy Cline 2018-04-30 16:46:50 UTC

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.

Comment 4 Jeremy Cline 2018-05-01 14:51:53 UTC

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 ***