Bug 102972 - Flickering since 4.11
Summary: Flickering since 4.11
Status: NEW
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/other (show other bugs)
Version: XOrg git
Hardware: All Linux (All)
: medium normal
Assignee: Default DRI bug account
QA Contact:
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2017-09-25 12:20 UTC by Lionel Le Folgoc
Modified: 2017-09-25 12:27 UTC (History)
0 users

See Also:
i915 platform:
i915 features:


Attachments
bisect log (drm) (1.82 KB, text/plain)
2017-09-25 12:20 UTC, Lionel Le Folgoc
no flags Details
dmesg with flickering (408.78 KB, text/plain)
2017-09-25 12:20 UTC, Lionel Le Folgoc
no flags Details
xrandr with flickering (10.61 KB, text/plain)
2017-09-25 12:21 UTC, Lionel Le Folgoc
no flags Details
dmesg without flickering (381.91 KB, text/plain)
2017-09-25 12:21 UTC, Lionel Le Folgoc
no flags Details
xrandr without flickering (10.61 KB, text/plain)
2017-09-25 12:21 UTC, Lionel Le Folgoc
no flags Details
(for reference only, first attempt at bisecting in drm/i915, it does not show the real first bad commit, see https://bugs.freedesktop.org/attachment.cgi?id=134458 instead) (1.94 KB, text/plain)
2017-09-25 12:27 UTC, Lionel Le Folgoc
no flags Details

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Description Lionel Le Folgoc 2017-09-25 12:20:28 UTC
Created attachment 134458 [details]
bisect log (drm)

Hi,

(I've only Intel hardware available but since git bisect shows the culprit in drm and not drm/i915, I've filed it against DRM/other, feel free to reassign)

Since 4.11, I've noticed major flickering on some displays I have (reproducible 100%). By flickering I mean the screen is mostly black and every few seconds I can see a flash with the screen content and it goes black again.
It only occurs with the preferred mode, i.e. when I force a modeline to another mode in xorg.conf the flickering does not occur.

I've tried all versions up to latest 4.14.0-rc2 and it is still reproducible, 4.10.x were fine. The display driver used (intel or modesetting) does not make a difference.

I tried on all hardware I have here (NUC gen4 d5420, NUC5i5 and NUC6i5SYB) and the behavior is the same. I tried miniDP and HDMI, and it does not change anything.

The captured logs below have been run on a NUC6i5SYB connected with miniDP, running CentOS 7.3, with the kernel 4.11.8 (from mainline, no ct7 or rhel patches). The git bisect was also run on this machine.

Git bisect identified fcc8a22cc9053a8d1bbb94833ec103cd5961feef as first bad commit.
With the log files below, 4.11.8-1 is "original" 4.11.8 kernel (bad), and 4.11.8-2 includes the commit reverted (good).

From the git bisect log and the fact it can be worked around with another modeline, I'm not even sure this is a regression in the kernel, as this might be that the screen is advertising something it cannot support properly...

Thanks.
Comment 1 Lionel Le Folgoc 2017-09-25 12:20:52 UTC
Created attachment 134459 [details]
dmesg with flickering
Comment 2 Lionel Le Folgoc 2017-09-25 12:21:21 UTC
Created attachment 134460 [details]
xrandr with flickering
Comment 3 Lionel Le Folgoc 2017-09-25 12:21:44 UTC
Created attachment 134461 [details]
dmesg without flickering
Comment 4 Lionel Le Folgoc 2017-09-25 12:21:59 UTC
Created attachment 134462 [details]
xrandr without flickering
Comment 5 Lionel Le Folgoc 2017-09-25 12:27:02 UTC
Created attachment 134463 [details]
(for reference only, first attempt at bisecting in drm/i915, it does not show the real first bad commit, see https://bugs.freedesktop.org/attachment.cgi?id=134458 instead)


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