Bug 92874 - FBC on HD4600 causes screen flickering on certain screen content
Summary: FBC on HD4600 causes screen flickering on certain screen content
Status: CLOSED INVALID
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Intel (show other bugs)
Version: unspecified
Hardware: x86-64 (AMD64) All
: medium normal
Assignee: Intel GFX Bugs mailing list
QA Contact: Intel GFX Bugs mailing list
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2015-11-09 21:03 UTC by Petr Kulhavy
Modified: 2017-07-24 22:44 UTC (History)
3 users (show)

See Also:
i915 platform: HSW
i915 features: display/FBC


Attachments
Video record of the issue (11.68 MB, application/octet-stream)
2015-11-09 21:16 UTC, Petr Kulhavy
no flags Details

Description Petr Kulhavy 2015-11-09 21:03:46 UTC
Machine: Asus "Zenbook" UX501
CPU: i7 4720HQ
GPU: Intel HD4600
Kernel 4.3.2
OS: Kubuntu 15.10

After enabling FBC with kernel option "i915.enable_fbc=1" the screen flickers with specific video content. Typically Firefox browser with some page. As an example the "https://01.org/linuxgraphics/community/kernel" at the default zoom level.

Please note that my notebook has 4k display. I have seen the issue only on the built-in panel, not on an external screen.

The flickering typically looks like the picture is switching between correct look and the same picture shifted down. The Y offset varies depending on the content. So does the flickering frequency. In the above example the offset is about half of the screen height.

If the content changes, e.g. change the zoom level in Firefox (on the above example it's sufficient to scroll down to the text so the picture disappears), the flickering changes or disappears.
Comment 1 Petr Kulhavy 2015-11-09 21:16:46 UTC
Created attachment 119524 [details]
Video record of the issue
Comment 2 Paulo Zanoni 2016-01-29 21:16:23 UTC
Hi

Does this problem still happen if you use the most recent drm-intel-nightly branch from http://cgit.freedesktop.org/drm-intel ?

Thanks,
Paulo
Comment 3 Paulo Zanoni 2016-10-28 11:39:38 UTC
Closing bug due to no response from the bug reporter in 10 months, plus the fact that we fixed a huge pile of FBC bugs after this bug was reported.

If you think the bug is still present, feel free to reopen it, but please test it against a newer Kernel with drm.debug=0xe and provide the dmesg output.

Thanks,
Paulo


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