func: static void ehci_writeback_async_complete_packet(EHCIPacket *p)
  {
      EHCIQueue *q = p->queue;
      int state;
      state = ehci_get_state(q->ehci, q->async);
      ehci_state_executing(q);
      ehci_state_writeback(q); /* Frees the packet! */
      if (!(q->qh.token & QTD_TOKEN_HALT)) {
          ehci_state_advqueue(q);
      ehci_set_state(q->ehci, q->async, state);