I had a kvm switch utilizing 5 hdmi cables, 4 for the pcs and one for input into the monitor and 4 usb cables.  By pressing a button on the front of the KVM switch I could toggle between the 4 PCs, BUT on Port one on the KVM I could not get the the mouse or keyboard to respond.  The mouse and keyboard functioned properly on the other 3 KVM ports.

Solution:

login to the pc on which the failed kvm port is connected.  you may have to move the USB dongle to that pc to gain access

check if autosuspend is causing your problem:
cat /sys/module/usbcore/parameters/autosuspend
if this returns a 2 then this is most likely your problem

do the following:
sudo nano /etc/default/grub

look for the following line:

GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash”

and change it to:

GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash usbcore.autosuspend=-1″

save the file

exit nano

sudo update-grub

sudo shutdown -Fr now (reboot that pc)

After rebooting, plug your usb dongle into your kvm switch

your mouse and keyboard should be functioning properly

log into your account and enter the cat command again:

cat /sys/module/usbcore/parameters/autosuspend

you should now see a “-1”