usb: dwc3: Ignore late xferNotReady event to prevent halt timeout

During a device-initiated disconnect, the End Transfer command resets
the event filter, allowing a new xferNotReady event to be generated
before the controller is fully halted. Processing this late event
incorrectly triggers a Start Transfer, which prevents the controller
from halting and results in a DSTS.DEVCTLHLT bit polling timeout.

Ignore the late xferNotReady event if the controller is already in a
disconnected state.

Fixes: 72246da ("usb: Introduce DesignWare USB3 DRD Driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/20250807090700.2397190-1-khtsai@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Kuen-Han Tsai

drivers/usb/dwc3/gadget.c

@@ -3777,6 +3777,15 @@ static void dwc3_gadget_endpoint_transfer_complete(struct dwc3_ep *dep,
 static void dwc3_gadget_endpoint_transfer_not_ready(struct dwc3_ep *dep,
 		const struct dwc3_event_depevt *event)
 {
+	/*
+	 * During a device-initiated disconnect, a late xferNotReady event can
+	 * be generated after the End Transfer command resets the event filter,
+	 * but before the controller is halted. Ignore it to prevent a new
+	 * transfer from starting.
+	 */
+	if (!dep->dwc->connected)
+		return;
+
 	dwc3_gadget_endpoint_frame_from_event(dep, event);
 
 	/*