ATW_TXCTL_OWN
((nexttx == firsttx) ? 0 : htole32(ATW_TXCTL_OWN));
sc->sc_txdescs[firsttx].at_ctl |= htole32(ATW_TXCTL_OWN);
#define ATW_TXSTAT_OWN ATW_TXCTL_OWN /* 0: not for transmission */