ATH9K_SLOT_TIME_9
if (us < ATH9K_SLOT_TIME_9 || us > ath9k_hw_mac_to_usec(ah, 0xffff)) {
(void) ath9k_hw_setslottime(ah, ATH9K_SLOT_TIME_9);
sc->sc_slottime = ATH9K_SLOT_TIME_9;
(void) ath9k_hw_setslottime(ah, ATH9K_SLOT_TIME_9);