DP1.2 daisy-chain flickering

[Stuart]

Hi all,

I have a NUC7i7BNH with the latest BIOS (0062) running Ubuntu 18.04 (uname -r = 4.15.0-15-generic). I have the NUC connected via USB-C to DisplayPort, to an Avocent SV340D KVM, then to a Dell U2415 which has DP1.2 enabled and is daisy-chainged to another Dell U2415 (DP1.2 disabled on the second monitor as per Dell instructions).

I am getting flickering whereby randomly display1 or display2 turn black and then back on again. When I disable DP1.2 on the display1, and therefore get a duplicate display (as opposed to extended) on display2, I get no flickering at all.

The same setup yields no flickering when running from a Windows 10 box, so don't think it is the monitors.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu6
ProcVersionSignature: Ubuntu 4.15.0-15.16-generic 4.15.15
Uname: Linux 4.15.0-15-generic x86_64
ApportVersion: 2.20.9-0ubuntu4
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Sat Apr 14 12:52:24 2018
DistUpgraded: Fresh install
DistroCodename: bionic
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation Device [8086:5927] (rev 06) (prog-if 00 [VGA controller])
   Subsystem: Intel Corporation Device [8086:2068]
InstallationDate: Installed on 2018-04-01 (12 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180401)
MachineType: Intel Corporation NUC7i7BNH
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-15-generic.efi.signed root=/dev/mapper/ubuntu--vg-root ro quiet splash
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/22/2018
dmi.bios.vendor: Intel Corp.
dmi.bios.version: BNKBL357.86A.0062.2018.0222.1644
dmi.board.name: NUC7i7BNB
dmi.board.vendor: Intel Corporation
dmi.board.version: J31145-307
dmi.chassis.type: 3
dmi.chassis.vendor: Intel Corporation
dmi.chassis.version: 2
dmi.modalias: dmi:bvnIntelCorp.:bvrBNKBL357.86A.0062.2018.0222.1644:bd02/22/2018:svnIntelCorporation:pnNUC7i7BNH:pvrJ31153-308:rvnIntelCorporation:rnNUC7i7BNB:rvrJ31145-307:cvnIntelCorporation:ct3:cvr2:
dmi.product.family: Intel NUC
dmi.product.name: NUC7i7BNH
dmi.product.version: J31153-308
dmi.sys.vendor: Intel Corporation
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.91-2
version.libgl1-mesa-dri: libgl1-mesa-dri 18.0.0~rc5-1ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx 18.0.0~rc5-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu3
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:18.0.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2

[Stuart (shutch)]

The flickering does not happen if I bypass the Avocent SV340D KVM and plug directly into the monitor. Any thoughts as to why this would happen?

[Stuart (shutch)]

@update. Started occurring even when bypassing the Avocent.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Stuart (shutch)]

Just wondering if there is any update on this?

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Paul White (paulw2u)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. We are sorry that we do not always have the capacity to review all reported bugs in a timely manner.

Ubuntu 18.04 (bionic) reached end-of-standard-support on May 31, 2023.

I'm setting the status of this bug to 'Incomplete' as it's not seen any activity for some time. If this is still an issue when using a currently maintained release of Ubuntu then please let us know which one(s) otherwise this bug report can be left to expire in approximately 60 days time.

[Launchpad Janitor (janitor)]

[Expired for xorg-server (Ubuntu) because there has been no activity for 60 days.]

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]