Level1Tech KVM enters unrecoverable state after AMD Driver crash

Hardware
,
1

I use the USB-C out of my AMD Radeon RX 6800 XT as the USB-C input for my USB-C Lvel1Techs KVM.

When the AMD Driver crashes (because it’s the year of Linux on the Desktop and I use HW acceleration) the KVM goes into an unrecoverable state where the only way any USB works again is to power cycle the KVM itself.

This is what happens.

  1. AMD Driver crashes
  2. I completely power off my computer by holding the power button.
  3. I wait 5 seconds
  4. I boot my computer

At this time neither the HID nor the USB3.0 hubs are functioning in the KVM.

I unplug and plugin the KVM (after waiting 5 seconds)

I am now able to use the HID / USB hub.

To be clear I feel that this is an issue inside the KVM because if I switch to the other input (a macbook pro in this case) I similarly am unable to use any USB until I power cycle the KVM.

Curious if there is anything I can do here - beyond the obvious (don’t make my life hard by using Desktop Linux)

To make it very clear I don’t blame the KVM for crashing the AMD driver, but I would like to be able to recover with out having to power-cycle the KVM.

2

Usually this type of issue is kind of outside the things i can reach from firmware. Usually whats crashing is a low level handshake to do with if the gpu wants power delivery. Its not so much the kvm crashes but the failure mode of the gpu is to tell the kvm to go away it doesnt handle power or data or display and it puts the pd chipset in a weird state.

The most common root cause is noise on the line from gpu to kvm so maybe worth trying shorter usb c to c csbles, or add a ferrite bead to the c cable at the kvm end

3

Thank you for your reply!

Does this survive a power off on the host system? I would have assumed that sort of state would not preserved after a power off, but perhaps it is.

Good to know, I will try this!