The Dell Inspiron 5775 is a Raven Ridge. The Enable Slot command timed
out when a USB device gets plugged:
[ 212.156326] xhci_hcd 0000:03:00.3: Error while assigning device slot ID
[ 212.156340] xhci_hcd 0000:03:00.3: Max number of devices this xHCI host supports is 64.
[ 212.156348] usb usb2-port3: couldn't allocate usb_device
AMD suggests that a delay before xHC suspends can fix the issue.
I can confirm it fixes the issue, so use the suspend delay quirk for
Raven Ridge's xHC.