Monitor does not wake up on input after DPMS turns it off, pressing the monitor power button wakes it up

[Douglas Silva]

After the screen turns off (for inactivity, screen lock, etc.), mouse or keyboard input won't bring it back. When I come back to the computer to resume my work, I have to wake the system up, and press the power button on the monitor. If I don't manually bring the monitor back on, the system will resume and the screen will remain off.

I believe this is a regression, because this cannot be reproduced in distributions as old as Debian Stretch 9. Any distribution newer than Debian causes this problem, no matter what Desktop Environment, what Display Manager or Screen Locker I choose. This is also not reproducible on Windows 10.

It's worth mentioning that this desktop runs the RX 560 AMD graphics card.
Also, this is my monitor: https://www.lg.com/in/monitors/lg-22MP58VQ

ProblemType: Bug
DistroRelease: Ubuntu 19.04
Package: linux-image-5.0.0-15-generic 5.0.0-15.16
ProcVersionSignature: Ubuntu 5.0.0-15.16-generic 5.0.6
Uname: Linux 5.0.0-15-generic x86_64
ApportVersion: 2.20.10-0ubuntu27
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: dsilva 1883 F.... pulseaudio
 /dev/snd/controlC1: dsilva 1883 F.... pulseaudio
CurrentDesktop: ubuntu:GNOME
Date: Mon May 27 22:45:13 2019
InstallationDate: Installed on 2019-05-26 (2 days ago)
InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Release amd64 (20190416)
IwConfig:
 enp2s0 no wireless extensions.

 lo no wireless extensions.
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 003: ID 0951:16bc Kingston Technology
 Bus 001 Device 002: ID 0951:16d2 Kingston Technology
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Gigabyte Technology Co., Ltd. B360M GAMING HD
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.0.0-15-generic root=/dev/mapper/ubuntu--vg-root ro quiet splash vt.handoff=1
RelatedPackageVersions:
 linux-restricted-modules-5.0.0-15-generic N/A
 linux-backports-modules-5.0.0-15-generic N/A
 linux-firmware 1.178.1
RfKill:

SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/14/2019
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: F12
dmi.board.asset.tag: Default string
dmi.board.name: B360M GAMING HD
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF12:bd03/14/2019:svnGigabyteTechnologyCo.,Ltd.:pnB360MGAMINGHD:pvrDefaultstring:rvnGigabyteTechnologyCo.,Ltd.:rnB360MGAMINGHD:rvrx.x:cvnDefaultstring:ct3:cvrDefaultstring:
dmi.product.family: Default string
dmi.product.name: B360M GAMING HD
dmi.product.sku: Default string
dmi.product.version: Default string
dmi.sys.vendor: Gigabyte Technology Co., Ltd.

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

This change was made by a bot.

[Kai-Heng Feng (kaihengfeng)]

Please test latest mainline kernel:
[1] https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.2-rc2/

[Douglas Silva (o-alquimista)]

Tested kernel 5.2-rc2. The issue is still reproducible.

To clarify it a bit more, let me explain that this happens when the screen turns off by inactivity (screen locks) and also when you suspend to RAM and then resume. The monitor will not turn back on when you press any key.

I can continue pressing keys and mouse buttons, but it will remain dark. I turn on the monitor manually, and I see the screen locker there showing in the password input box that I've been pressing keys while the monitor was dark.

However, when the computer hibernates or is shut down, and you turn it on again, the monitor will go from standby to the powered on state, as it should.