16 May 2021 (Sun)

10:24:38 # Life Memo on using a KVM switch with my Debian desktop and ChromeBox. KVM these days mean Kernel virtualization things but before it used to mean KVM switch; where PS/2 and DSUB15 pin was a popular interface. These days it's USB + HDMI; USB-C with dP alt mode would make connections simpler including power supply, but that doesn't exist as much. This ends up 3 cables each for PC and display, with 2 USB cables and 1 HDMI cable per endpoint. I bought a cheap manual switcher. Automatic switcher can be annoying especially when suspend-resume case, there's no rational behavior, especially when I want to wake devices through keyboard. Having a wired remote control was good because although the device itself is compact, the 9 or so cables running out of it is bulky and I moved it under my desk to hide it from my view. Sometimes suspending / resume causes issues with the USB hub, it's recognized as SuperTop USB Hub, and from Linux kernel it seems like hub is disconnected and reconnected, however on reinitialization sometimes USB hub fails to be initialized. That results in keyboard not working, but re-connecting the USB cable fixes the issue. Sound is recorded via USB mixer, and played back via HDMI audio, video is recorded via USB camera. These things didn't exist back in the old KVM days, maybe they used audio cables.

[105071.287587] usb usb3-port2: Cannot enable. Maybe the USB cable is bad?
[105072.187749] usb usb3-port2: Cannot enable. Maybe the USB cable is bad?
[105072.187836] usb usb3-port2: attempt power cycle
Junichi Uekawa