usbd_tt
struct usbd_tt *usb_tt;
struct usbd_tt *tts = NULL;
sizeof(struct usbd_tt), M_USBDEV, M_NOWAIT);
(UHUB_IS_SINGLE_TT(sc) ? 1 : hub->nports) * sizeof(struct usbd_tt));
struct usbd_tt *tt; /* Transaction translator (if any) */