Booting the otg profile with /etc/usbmode = device made S72usbmode's
`usb-mode device` log, on every single boot:
xhci-hcd xhci-hcd.0.auto: Host not halted after 16000 microseconds.
xhci-hcd xhci-hcd.0.auto: Host controller not halted, aborting reset.
dwc3_core_init() leaves GCTL.PRTCAPDIR = OTG(3) and this 4.9 dwc3 never
moves off OTG on its own. xhci-hcd binds and registers both buses on top
of that anyway, but it is not actually driving the port -- so unbinding
straight from OTG asks xhci_halt() to halt a host that was never really
running, and it times out.
The gadget composed regardless, so this was cosmetic in practice, but it
left the host controller un-halted: exactly the live-DMA-engine state the
unbind is there to avoid.
Flip the controller to host before unbinding, so the already-bound xHCI
is genuinely running and the unbind halts cleanly. A switch from host is
already in that state, so only boot pays for the extra flip.
Measured on gk7205v200 (Xiongmai IPC_GK7205V200_50H20AI_S38): 5/5 cold
boots warned before, 0/5 after. Runtime host<->device round trips stay
clean and still take ~0.35s, with no reboot and no majestic restart.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
