LE VM on proxmox (intel n150): no HDMI output on tv - displays ok on monitor

    I've made an experimental howto regarding hosting LE as a VM in proxmox, with GPU pass-through to LE, as per [x86-64] LE 12 as a Proxmox VM with GPU pass-through . This setup worked (visually at least) when the system was connected to a computer monitor.

    Tried to connect it to my 15-year old samsung. The VM starts, the PVE console screen gets replaced with a blank screen and the I get the no signal on HDMI from the TV.

    getedid on the LE sees no interfaces:

    Code
    # tail /sys/class/drm/*/status
==> /sys/class/drm/card0-DP-1/status <==
disconnected
==> /sys/class/drm/card0-HDMI-A-1/status <==
disconnected

    The system does respond. From the web interface, it shows that for some reason instead of going 1080p60, it switched to 1280x720. I can see this in the kodi.log as well:

    dmesg:

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    PS: There's also the issue that only bluetooth audio is found. When creating the VM I did not pass through the audio device, thinking that it would not be needed since audio is passed over in digital format. I'll pass through the host's audio device as well.

    JEEEEZAAAZZZZ!!!!!!!

    After fumbling with a zillion articles, I recalled that this mini pc has two HDMI outputs. I connected it to the other one and presto! LE is alive and in 1080p glory. What's strange is that both outputs worked to display the PVE console output. It's when LE started that only one worked. My hunch is that the 2nd HDMI is some sort of DP in disguise...

    The bad news it that I have no sound devices. My initial tries to pass through the PCI intel audio device failed, possibly because that one is part of an IOMMU group. Whenever I start the VM I get an error that the device has no handle to be initialized :(

    If anyone has an idea on how to proceed, please let me know.

    I've overcame this issue as well (with a somewhat important caveat): I have full video and audio passed through to my television, and I'll update the howto accordingly.

    The caveat is that after terminating the LE VM, the intel PCI audio becomes inaccessible :/ The only cure is to re-start the hypervisor again. For always-on LE VMs that's not an issue obviously, but I can kiss the VM shutdown/wake-on-LAN functionality goodbye.

    Quote from cosmos

    My hunch is that the 2nd HDMI is some sort of DP in disguise...

    Most modern/cheaper Intel boxes derive HDMI from DP using an LSPCON chip as this multi-purpose (DP/HDMI) chipset is cheaper to implement than using dedicated DP and HDMI transceivers. LSPCON chips and their Windows oriented and buggy firmwares have been "the gift that keeps on giving" for problems since they first appeared in NUC devices about a decade ago.

    Wish I have known that :) If I had used getedid I'd see that instead of HDMI-1` and -2, there was HDMI-1 and DP-1 (even thought the GMKtec offered two HDMI ports...)