KVM-Switch Loss of Video-Out signal after switching back to my PC after

I found this, but it seems to be left unanswered:

Since a few days im using a 2xKVM-Switch to switch between my working and private PC

My problem is, that when i switch back to my Linux-Desktop-PC (PC1) after a longer time working on (PC2), the display stays black with no signal.
Even if i re-plugin the HDMI cable again, nothing happens.

Does anyone know if i can try to solve this?
Are there Settings for my NVIDIA-Card i can check?

Only thing that helps is a “blind-reboot” by using the reset-button, which can lead to loss of unsaved changes.

My system:

  Kernel: 5.19.11-1-MANJARO arch: x86_64 bits: 64 compiler: gcc v: 12.2.0
    Desktop: awesome v: 4.3-1538-g4a140ea5e vt: 1 dm: SDDM
    Distro: Manjaro Linux base: Arch Linux
  Type: Desktop Mobo: ASUSTeK model: Z170 PRO GAMING v: Rev X.0x
    serial: <superuser required> UEFI-[Legacy]: American Megatrends v: 3805
    date: 05/16/2018
  Info: quad core model: Intel Core i7-6700K bits: 64 type: MT MCP
    smt: enabled arch: Skylake-S level: v3 rev: 3 cache: L1: 256 KiB
    L2: 1024 KiB L3: 8 MiB
  Speed (MHz): avg: 998 high: 1200 min/max: 800/4200 cores: 1: 837 2: 933
    3: 1116 4: 933 5: 965 6: 1200 7: 800 8: 1200 bogomips: 64026
  Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
  Device-1: NVIDIA GP106 [GeForce GTX 1060 6GB] vendor: Gigabyte
    driver: nvidia v: 515.76 arch: Pascal pcie: speed: 8 GT/s lanes: 16 ports:
    active: none off: HDMI-A-1 empty: DP-1,DVI-D-1,DVI-D-2 bus-ID: 01:00.0
    chip-ID: 10de:1c03 class-ID: 0300
  Display: x11 server: X.Org v: 21.1.4 with: Xwayland v: 22.1.3 driver: X:
    loaded: nvidia unloaded: vesa gpu: nvidia,nvidia-nvswitch display-ID: :0
    screens: 1
  Screen-1: 0 s-res: 3440x1440 s-dpi: 109 s-size: 802x342mm (31.57x13.46")
    s-diag: 872mm (34.33")
  Monitor-1: HDMI-A-1 mapped: HDMI-0 note: disabled model: LG (GoldStar)
    ULTRAWIDE serial: <filter> res: 3440x1440 hz: 50 dpi: 109
    size: 800x335mm (31.5x13.19") diag: 867mm (34.1") modes: max: 3440x1440
    min: 640x480
  OpenGL: renderer: NVIDIA GeForce GTX 1060 6GB/PCIe/SSE2 v: 4.6.0 NVIDIA
    515.76 direct render: Yes

Hi there @SHUred

I’m experiencing the same problem with my AMD Radeon RX Vega 56 graphicscard and two Dell P2722HE Monitors (Daisychaining)

Could you resolve the issue in the meantime?
Thank you for your answer.

Hey man,
sorry i could never solve this problem by 100%

In the meantime is switched to Fedora
Did not experience this anymore

So for you this is a hint that it should definetely some Software/Driver related problem

Interesting, that in your case it is AMD

Hey there @SHUred
Thank you for your answer.

Maybe, I just figured out the answer, according to this ArchForum Post:
ArchForum → Kernel & Hardware → [SOLVED] Terminal disappears when using kvm switch,then switching back

(Sorry, can’t post link somehow. I would, if I could)

He tells about, that the graphicscard is registered as an audio device (according to lspci), even though his monitors didn’t have built-in speakers.

So what he did, is blacklisting the snd_hda_codec_hdmi kernel module and then it started to work again.

I did the same, in the hopes it changes something. AND IT DID!

I just added in the GRUB_CMDLINE_LINUX_DEFAULT the part module_blacklist=snd_hda_codec_hdmi, rebuilt the grub-config and rebooted my PC.
After switching between back and fourth my machines, the monitors always responded and gave a signal.

I though I would let you know that, maybe you’ll try again Manjaro with this kind of workaround and see what happens. :slight_smile:

Have a great day.
Cheers mate

1 Like

Great job