[Bug 97551] New: Blank screen and/or screen flickering when leaving screen powersave or after login prompt (LightDM)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=97551

            Bug ID: 97551
           Summary: Blank screen and/or screen flickering when leaving
                    screen powersave or after login prompt (LightDM)
           Product: DRI
           Version: XOrg git
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: walid.moghrabi at lezard-visuel.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

Created attachment 126135
  --> https://bugs.freedesktop.org/attachment.cgi?id=126135&action=edit
Full dmesg

Detailed system information:
============================
-- system architecture: x86_64
-- kernel version: 4.4.0-36-generic
-- Linux distribution: Ubuntu 16.04LTS Desktop
-- Machine or mother board model: Dell Latitude E7250 (BIOS: A13)
-- Display connector: DVI on E Series Dock Station, laptop screen off but I
tried in many different configurations with different connections (DVI+VGA on
station, external screen connected with HDMI directly on the laptop, dual DP on
station, ... same situation in every situation. No problem on the laptop screen
in mono display situation)
-- Intel driver version : xserver-xorg-video-intel
2.99.917+git1608291931.74e4c1~gd~x (amd64)


I'm running my Dell E7250 laptop with Ubuntu 16.04LTS (but had the same problem
with Ubuntu 15.10) in a multiple head setup (2 external screens in 1080p
connected with DVI on a Dell E Series docking station, laptop screen is off so
using only the 2 external displays).

I have a very annoying problem with multiple displays and the Intel driver
under Linux, there are 2 situations with same behaviour :

At first, when LightDM prompt for my login, only one screen is switched on in
low resolution (probably 640x480)

After login in from LightDM prompt, if I'm too quick (that say, if I don't wait
a few seconds before the second screen is correctly detected), then once logged
sometimes my secondary display is flickering or even sometimes not detected
(and thus blank) at all.


Second situation, when the screen goes blank when iddled (when I leave my
laptop a few minutes for example), when getting back, at the login prompt (this
time in the correct resolution), if I don't wait for the secondary screen to
light up (and it lights up a lot slower than the primary one), then I encounter
the same behaviour which means flickering screen (most of the times) or even,
black screen. 

This never happens to the primary display, only the secondary.

In both situation, as a workaround, I found that moving to a console TTY (with
Ctrl+Alt+F5 for example) then getting back to the graphical display (with
Ctrl+Alt+F7) tends to recover a normal situation.
This works 90% of the times, sometimes not and I just do this again and then it
works.

I would alsao add that in rare situations, the Xorg server simply crashes and
the whole session with opened application is lost.

Least to say that it is extremely annoying and this last for a long time now
since I have this setup for more than a year now and tried many kernel releases
and intel driver version.
Currently running the latest Ubuntu 16.04LTS kernel and intel nightly driver
thanks to oibaf's PPA but still, the problem persists.

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