[Bug 93772] New: 4k eDP display blanks on intel-drm-nightly

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=93772

            Bug ID: 93772
           Summary: 4k eDP display blanks on intel-drm-nightly
           Product: DRI
           Version: DRI git
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: sami.liedes at vincit.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

Created attachment 121132
  --> https://bugs.freedesktop.org/attachment.cgi?id=121132&action=edit
dmesg

Possibly related: Bug 80896, Bug 92084

On a Dell Latitude E7450, using a drm-intel-nightly kernel from today, an
external 4k display shows picture on display manager login screen, but quickly
blanks after typing credentials and starting KDE.

Reproduction is easy: This practically always happens within 10 seconds after
trying to log in.

The mbim-proxy soft lockup BUG in the dmesg is probably not related; I'm only
seeing that on drm-intel-nightly, not on mainline 4.4 or drm-intel-next.

The same outward symptoms are present on ubuntu's 4.2 kernel, 4.4,
drm-intel-next and drm-intel-nightly.

dmesg with drm.debug=0xe and xrandr --verbose output from drm-intel-nightly
boot attached.

*Sometimes* changing the external display's resolution to 1920x1080 helps wake
the display up.

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