L1KVM DP 1.2 report

A lot of the threads are old, so I thought I’d just post one reporting my more recent results.

Systems used:

  • Macbook Pro 16" (2019 - Radeon 5500M)
    • Startech_com CDP2DP USB-C to Displayport
    • Some generic USB-C to USB 3.0 A (AmazonBasics maybe?)
  • Gaming PC w/ Geforce GTX 980 Ti - Windows 10. I did the registry hack to default Windows to 2560x1440 (search past threads here for info)
  • Linux PC - Asus Q87 board with i5-4590T, onboard graphics. I’m testing various distros and desktops (more on that later)

Peripherals:

  • Lenovo L24q-20 (2560x1440 60hz IPS)
  • Plugable USB 3.0 hub, plugged into a USB3 port on the KVM
    • Webcam
    • Audio
    • Kinesis Freestyle Edge keyboard
  • Logitech K400r wireless keyboard - unified receiver on KVM hid port
  • USB mouse - on KVM hid port

I have a mix of cables from L1 and Tripp-Lite (from my past KVM), no specific problems running at 2560x1440x60-67hz

Each of the systems seems to be working fine and resuming from sleep after giving them a few seconds for monitor detection.

Here’s a few gotchas:

  • The mac moves windows to the lower left corner and resizes them to something around 1600x1000. I guess I’ll need to find some 3rd party window manager to tile these for me
  • The mac seems to wake from the mouse (plugged to the HID port) but not the keyboard on the USB3 hub. Not a big deal
  • The mac takes the longest to resume and detect the monitor - close to 10 seconds
  • The Kinesis Freestyle Edge won’t work on the HID ports. It reports as 3 separate HID devices for some reason.

Here’s the Kinesis’s USB topology:

/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/15p, 480M
    |__ Port 4: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M
        |__ Port 4: Dev 34, If 0, Class=Hub, Driver=hub/4p, 480M
            |__ Port 1: Dev 35, If 0, Class=Hub, Driver=hub/4p, 480M
                |__ Port 1: Dev 36, If 2, Class=Human Interface Device, Driver=usbhid, 12M
                |__ Port 1: Dev 36, If 0, Class=Human Interface Device, Driver=usbhid, 12M
                |__ Port 1: Dev 36, If 1, Class=Human Interface Device, Driver=usbhid, 12M

How does this compare to my old solution?

I’m happy to finally have 4 ports so I can run all my systems in less space.

Previously I was using the Tripp Lite B004-DP2UA2-K. It also had problems with the Kinesis keyboard so I used a similar setup with a USB 2 hub to handle all the stuff I needed. Because it had EDID persistence systems switched slightly faster, but the KVM itself would also hang once every few weeks. I had to unplug everything to power cycle it, then use a dumb keyboard and some magic keystrokes to set it back into USB hub compatibility mode.

So about Linux desktops…

One of the reasons I was so eager to set this up was for testing different desktop environments. Wayland compositors tend to behave nicely in VMs with the QXL driver, but the experience varies a lot on hardware. So far I have tried:

  • Fedora 33 Workstation - default Gnome setup has a Wayland compositor on my Intel integrated graphics. It works great, and can handle KVM switching
  • Fedora rawhide (which will eventually be 34) with KDE Plasma - bad stuff happens when the monitor is switched off. The logged in user session in “VT2” goes blank, and the SDDM on “VT1” already shows a user logged in. I’ll be digging into this more to make sure bugs are fixed.
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I’ll be reserving this post for info on the KDE Plasma crash.

I’m in the process of getting logs but these threads seem very similar:

  • https bugs kde org/show_bug.cgi?id=420160
  • https gitlab com/kwinft/kwinft/-/issues/86

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