DisplayPort connection gets lost when using a KVM switch

I use a DisplayPort KVM switch for my desktop running Manjaro and a Windows laptop.

Everything was working great. However, I needed to reinstall Manjaro. Now, when I switch from the Manjaro desktop to the laptop and then back to the desktop, all I get is a black screen. For some reason, my system is no longer able to reconnect to DisplayPort.

Can anyone help?

inxi -Fxxxrz

System:
  Kernel: 5.18.5-1-MANJARO arch: x86_64 bits: 64 compiler: gcc v: 12.1.0
    Desktop: Xfce v: 4.16.0 tk: Gtk v: 3.24.29 info: xfce4-panel, plank
    wm: kwin_x11 vt: 7 dm: LightDM v: 1.30.0 Distro: Manjaro Linux
    base: Arch Linux
Machine:
  Type: Desktop Mobo: Micro-Star model: B450 TOMAHAWK MAX (MS-7C02) v: 1.0
    serial: <superuser required> UEFI: American Megatrends v: 3.50
    date: 11/07/2019
CPU:
  Info: 6-core model: AMD Ryzen 5 3600X bits: 64 type: MT MCP smt: enabled
    arch: Zen 2 rev: 0 cache: L1: 384 KiB L2: 3 MiB L3: 32 MiB
  Speed (MHz): avg: 4249 high: 4250 min/max: N/A cores: 1: 4250 2: 4250
    3: 4247 4: 4250 5: 4250 6: 4250 7: 4250 8: 4250 9: 4250 10: 4250 11: 4250
    12: 4250 bogomips: 102045
  Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 svm
Graphics:
  Device-1: AMD Navi 10 [Radeon RX 5600 OEM/5600 XT / 5700/5700 XT]
    vendor: Micro-Star MSI driver: amdgpu v: kernel arch: RDNA 1 pcie:
    speed: 16 GT/s lanes: 16 ports: active: DP-3 empty: DP-1,DP-2,HDMI-A-1
    bus-ID: 28:00.0 chip-ID: 1002:731f class-ID: 0300
  Device-2: Logitech Webcam C310 type: USB driver: snd-usb-audio,uvcvideo
    bus-ID: 3-2.4:6 chip-ID: 046d:081b class-ID: 0102 serial: <filter>
  Display: x11 server: X.Org v: 21.1.3 compositor: kwin_x11 driver: X:
    loaded: amdgpu unloaded: modesetting,radeon alternate: fbdev,vesa
    gpu: amdgpu display-ID: :0.0 screens: 1
  Screen-1: 0 s-res: 3440x1440 s-dpi: 96 s-size: 910x381mm (35.83x15.00")
    s-diag: 987mm (38.84")
  Monitor-1: DP-3 mapped: DisplayPort-2 model: 34CHR res: 3440x1440 hz: 60
    dpi: 110 size: 797x334mm (31.38x13.15") diag: 864mm (34") modes:
    max: 3440x1440 min: 720x400
  OpenGL:
    renderer: AMD Radeon RX 5700 (navi10 LLVM 13.0.1 DRM 3.46 5.18.5-1-MANJARO)
    v: 4.6 Mesa 22.1.1 direct render: Yes
Audio:
  Device-1: C-Media CMI8788 [Oxygen HD Audio] vendor: ASUSTeK Xonar DSX
    driver: snd_virtuoso v: kernel bus-ID: 3-2.1.1:5 bus-ID: 22:00.0
    chip-ID: 0d8c:016c chip-ID: 13f6:8788 class-ID: 0300 class-ID: 0401
  Device-2: AMD Navi 10 HDMI Audio driver: snd_hda_intel v: kernel pcie:
    speed: 16 GT/s lanes: 16 bus-ID: 28:00.1 chip-ID: 1002:ab38 class-ID: 0403
  Device-3: C-Media USB Advanced Audio Device type: USB
    driver: hid-generic,snd-usb-audio,usbhid
  Device-4: GCE--Pro . XtremPro X1 USB DAC type: USB driver: snd-usb-audio
    bus-ID: 3-2.3:4 chip-ID: 21db:0066 class-ID: 0102 serial: <filter>
  Device-5: Logitech Webcam C310 type: USB driver: snd-usb-audio,uvcvideo
    bus-ID: 3-2.4:6 chip-ID: 046d:081b class-ID: 0102 serial: <filter>
  Sound Server-1: ALSA v: k5.18.5-1-MANJARO running: yes
  Sound Server-2: JACK v: 1.9.21 running: no
  Sound Server-3: PulseAudio v: 16.0 running: yes
  Sound Server-4: PipeWire v: 0.3.52 running: yes
Network:
  Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet
    vendor: Micro-Star MSI driver: r8169 v: kernel pcie: speed: 2.5 GT/s
    lanes: 1 port: d000 bus-ID: 23:00.0 chip-ID: 10ec:8168 class-ID: 0200
  IF: enp35s0 state: up speed: 1000 Mbps duplex: full mac: <filter>
Drives:
  Local Storage: total: 2.11 TiB used: 549.39 GiB (25.5%)
  ID-1: /dev/nvme0n1 vendor: Samsung model: SSD 970 EVO Plus 250GB
    size: 232.89 GiB speed: 31.6 Gb/s lanes: 4 type: SSD serial: <filter>
    rev: 1B2QEXM7 temp: 44.9 C scheme: GPT
  ID-2: /dev/sda vendor: Samsung model: SSD 860 EVO 1TB size: 931.51 GiB
    speed: 6.0 Gb/s type: SSD serial: <filter> rev: 3B6Q scheme: GPT
  ID-3: /dev/sdb vendor: Western Digital model: WD10EZEX-08WN4A0
    size: 931.51 GiB speed: 6.0 Gb/s type: HDD rpm: 7200 serial: <filter>
    rev: 1A01 scheme: MBR
  ID-4: /dev/sdc type: USB vendor: Samsung model: Flash Drive
    size: 59.75 GiB type: SSD serial: <filter> rev: 1100 scheme: MBR
Partition:
  ID-1: / size: 212.5 GiB used: 13.97 GiB (6.6%) fs: ext4 dev: /dev/nvme0n1p3
  ID-2: /boot/efi size: 299.4 MiB used: 312 KiB (0.1%) fs: vfat
    dev: /dev/nvme0n1p2
  ID-3: /home size: 915.82 GiB used: 535.42 GiB (58.5%) fs: ext4
    dev: /dev/sda1
Swap:
  ID-1: swap-1 type: partition size: 15.62 GiB used: 0 KiB (0.0%)
    priority: -2 dev: /dev/nvme0n1p1
Sensors:
  System Temperatures: cpu: N/A mobo: N/A gpu: amdgpu temp: 58.0 C
    mem: 64.0 C
  Fan Speeds (RPM): N/A gpu: amdgpu fan: 849
Repos:
  Packages: pacman: 1361
  Active pacman repo servers in: /etc/pacman.d/mirrorlist
    1: http://manjaro.mirrors.theom.nz/stable/$repo/$arch
    2: https://manjaro.kyberorg.fi/stable/$repo/$arch
    3: https://mirror.moson.org/manjaro/stable/$repo/$arch
Info:
  Processes: 309 Uptime: 20m wakeups: 0 Memory: 15.57 GiB
  used: 3.93 GiB (25.3%) Init: systemd v: 251 default: graphical Compilers:
  gcc: 12.1.0 clang: 13.0.1 Shell: Zsh v: 5.9 default: Bash v: 5.1.16
  running-in: yakuake inxi: 3.3.19

see for update UEFI motherboard ( not version beta )
https://fr.msi.com/Motherboard/B450-TOMAHAWK-MAX/support

I have the same problem. I added a power button on the KVM switch’s power adapter, and power cycling it brings the monitor back to life.

Thanks for the replies. I managed to fix it by adding a custom modeline and applying it to X.org.

See: xrandr - ArchWiki

Here’s my configuration:

Section "Monitor"
    Identifier "DisplayPort-2"
    Modeline "3440x1440_144.00"  1086.75  3440 3744 4128 4816  1440 1443 1453 1568 -hsync +vsync
    Option "PreferredMode" "3440x1440_144.00"
EndSection

Section "Screen"
    Identifier "Screen0"
    Monitor "DisplayPort-2"
    DefaultDepth 24
    SubSection "Display"
        Modes "3440x1440_144.00"
    EndSubSection
EndSection

Section "Device"
     Identifier "AMD"
     Driver "amdgpu"
EndSection

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