Re: [Bug 1813663] Re: External monitors does not work anymore 4.15.0-44

As stated in bug 1813831 thread, the issue is related to a change in the
graphic driver's DPMS sequence. It was introduced in 4.15.0-44, and
reverted in 4.15.0-45 made available for testing in the other bug's thread.

Meaning that it's not related to thunderbolt docks, nor docks at all,
but to the display driver initializing the screen(s) through DPMS. My
Dell 9370 shows the issue on each boot with -44  even when not connected
to any external peripheral / dock / display, just with its internal screen.

The issue is totally gone with -45.

The DPMS change revert was already committed to upstream kernel patch
train.

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https://bugs.launchpad.net/bugs/1813663

Title:
External monitors does not work anymore 4.15.0-44

Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Bionic:
Fix Committed

Bug description:
I am using a docking station for my laptop. After install the
4.15.0-44 update my external monitors goes undetected after logging in
or having the laptop closed.

I am on 18.04.1 LTS with Intel® HD Graphics 620 (Kaby Lake GT2)
Graphics.

Going back to the 4.15.0-43 version makes it all work fine again.
---
ProblemType: Bug
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: jonas 2407 F.... pulseaudio
CurrentDesktop: ubuntu:GNOME
DistroRelease: Ubuntu 18.04
HibernationDevice: RESUME=UUID=80397b76-2ded-4f7d-adbf-dfdface8e2d4
InstallationDate: Installed on 2018-10-17 (103 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
MachineType: LENOVO 20HF004MMX
Package: linux (not installed)
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-44-generic root=UUID=64cf1582-d574-4e2f-a40a-7942c40caf5d ro quiet splash vt.handoff=1
ProcVersionSignature: Ubuntu 4.15.0-44.47-generic 4.15.18
RelatedPackageVersions:
linux-restricted-modules-4.15.0-44-generic N/A
linux-backports-modules-4.15.0-44-generic N/A
linux-firmware 1.173.3
Tags: bionic
Uname: Linux 4.15.0-44-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip docker kvm lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 09/14/2018
dmi.bios.vendor: LENOVO
dmi.bios.version: N1WET51W (1.30 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20HF004MMX
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrN1WET51W(1.30):bd09/14/2018:svnLENOVO:pn20HF004MMX:pvrThinkPadT470s:rvnLENOVO:rn20HF004MMX:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:
dmi.product.family: ThinkPad T470s
dmi.product.name: 20HF004MMX
dmi.product.version: ThinkPad T470s
dmi.sys.vendor: LENOVO

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