[Bug 97311] New: External screens connected through a daisy-chained Display Port are randomly flickering

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=97311

            Bug ID: 97311
           Summary: External screens connected through a daisy-chained
                    Display Port are randomly flickering
           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: cristi.magherusan at gmail.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

At work I recently bought a new primary monitor for my laptop's external
dual-screen setup. After a bit of research it turned out I need to connect it
in a daisy-chain DisplayPort setup, otherwise the resolution of my older second
screen would be limited to 1024x768.

As soon as figured out what I needed to do and I set everything up, all the
monitors started working in their native resolution, but the external screens
started to randomly turn black for like half a second, but not both at the same
time, then again work well for a while until the next half-second blackout.

With the same kernel, the same monitors as well as the previous monitors
configured to use both my video outputs didn't have this flockering issue, nor
did I see it on the other external monitor that I connect at home.

These are my system specs:
OS: Ubuntu Xenial x86_64
Kernel: 4.7.0-040700rc5-lowlatency from
http://kernel.ubuntu.com/~kernel-ppa/mainline/, installed before because of a
similar bug #95176, which used to manifest on my laptop's screen.

lspci output:                                                                  
                                                                             
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated
Graphics Controller (rev 0b)
00:03.0 Audio device: Intel Corporation Haswell-ULT HD Audio Controller (rev
0b)
00:14.0 USB controller: Intel Corporation 8 Series USB xHCI HC (rev 04)
00:16.0 Communication controller: Intel Corporation 8 Series HECI #0 (rev 04)
00:16.3 Serial controller: Intel Corporation 8 Series HECI KT (rev 04)
00:19.0 Ethernet controller: Intel Corporation Ethernet Connection I218-LM (rev
04)
00:1b.0 Audio device: Intel Corporation 8 Series HD Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 1 (rev e4)
00:1c.3 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 4 (rev e4)
00:1c.4 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 5 (rev e4)
00:1d.0 USB controller: Intel Corporation 8 Series USB EHCI #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation 8 Series LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 8 Series SATA Controller 1 [AHCI
mode] (rev 04)
00:1f.3 SMBus: Intel Corporation 8 Series SMBus Controller (rev 04)
02:00.0 Network controller: Intel Corporation Wireless 7260 (rev 73)
03:00.0 SD Host controller: O2 Micro, Inc. SD/MMC Card Reader Controller (rev
01)

The dmesg output doesn't show any messages related to the intel driver, so
that's why I didn't attach it, but if this information is not enough I can
produce more logs upon request.

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