xhci: add helper that checks for unhandled events on a event ring

Add unhandled_event_trb() that returns true in case xHC hardware has
written new event trbs to the event ring that driver has not yet handled.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/20240217001017.29969-8-quic_wcheng@quicinc.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -113,6 +113,12 @@ static bool last_td_in_urb(struct xhci_td *td)
 	return urb_priv->num_tds_done == urb_priv->num_tds;
 }
 
+static bool unhandled_event_trb(struct xhci_ring *ring)
+{
+	return ((le32_to_cpu(ring->dequeue->event_cmd.flags) & TRB_CYCLE) ==
+		ring->cycle_state);
+}
+
 static void inc_td_cnt(struct urb *urb)
 {
 	struct urb_priv *urb_priv = urb->hcpriv;
@@ -2973,9 +2979,8 @@ static int xhci_handle_event(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
 	}
 
 	event = ir->event_ring->dequeue;
-	/* Does the HC or OS own the TRB? */
-	if ((le32_to_cpu(event->event_cmd.flags) & TRB_CYCLE) !=
-	    ir->event_ring->cycle_state)
+
+	if (!unhandled_event_trb(ir->event_ring))
 		return 0;
 
 	trace_xhci_handle_event(ir->event_ring, &event->generic);