* ath_dynack_ewma - EWMA (Exponentially Weighted Moving Average) calculation
  *
  */
-static inline u32 ath_dynack_ewma(u32 old, u32 new)
+static inline int ath_dynack_ewma(int old, int new)
 {
-       return (new * (EWMA_DIV - EWMA_LEVEL) + old * EWMA_LEVEL) / EWMA_DIV;
+       if (old > 0)
+               return (new * (EWMA_DIV - EWMA_LEVEL) +
+                       old * EWMA_LEVEL) / EWMA_DIV;
+       else
+               return new;
 }
 
 /**
  */
 static void ath_dynack_compute_ackto(struct ath_hw *ah)
 {
-       struct ath_node *an;
-       u32 to = 0;
-       struct ath_dynack *da = &ah->dynack;
        struct ath_common *common = ath9k_hw_common(ah);
+       struct ath_dynack *da = &ah->dynack;
+       struct ath_node *an;
+       int to = 0;
 
        list_for_each_entry(an, &da->nodes, list)
                if (an->ackto > to)
                                        an->ackto = ath_dynack_ewma(an->ackto,
                                                                    ackto);
                                        ath_dbg(ath9k_hw_common(ah), DYNACK,
-                                               "%pM to %u\n", dst, an->ackto);
+                                               "%pM to %d [%u]\n", dst,
+                                               an->ackto, ackto);
                                        if (time_is_before_jiffies(da->lto)) {
                                                ath_dynack_compute_ackto(ah);
                                                da->lto = jiffies + COMPUTE_TO;
  * @ah: ath hw
  * @skb: socket buffer
  * @ts: tx status info
+ * @sta: station pointer
  *
  */
 void ath_dynack_sample_tx_ts(struct ath_hw *ah, struct sk_buff *skb,
-                            struct ath_tx_status *ts)
+                            struct ath_tx_status *ts,
+                            struct ieee80211_sta *sta)
 {
        struct ieee80211_hdr *hdr;
        struct ath_dynack *da = &ah->dynack;
                    ieee80211_is_assoc_resp(hdr->frame_control) ||
                    ieee80211_is_auth(hdr->frame_control)) {
                        ath_dbg(common, DYNACK, "late ack\n");
+
                        ath9k_hw_setslottime(ah, (LATEACK_TO - 3) / 2);
                        ath9k_hw_set_ack_timeout(ah, LATEACK_TO);
                        ath9k_hw_set_cts_timeout(ah, LATEACK_TO);
+                       if (sta) {
+                               struct ath_node *an;
+
+                               an = (struct ath_node *)sta->drv_priv;
+                               an->ackto = -1;
+                       }
                        da->lto = jiffies + LATEACK_DELAY;
                }
 
 
 void ath_dynack_init(struct ath_hw *ah);
 void ath_dynack_sample_ack_ts(struct ath_hw *ah, struct sk_buff *skb, u32 ts);
 void ath_dynack_sample_tx_ts(struct ath_hw *ah, struct sk_buff *skb,
-                            struct ath_tx_status *ts);
+                            struct ath_tx_status *ts,
+                            struct ieee80211_sta *sta);
 #else
 static inline void ath_dynack_init(struct ath_hw *ah) {}
 static inline void ath_dynack_node_init(struct ath_hw *ah,
                                            struct sk_buff *skb, u32 ts) {}
 static inline void ath_dynack_sample_tx_ts(struct ath_hw *ah,
                                           struct sk_buff *skb,
-                                          struct ath_tx_status *ts) {}
+                                          struct ath_tx_status *ts,
+                                          struct ieee80211_sta *sta) {}
 #endif
 
 #endif /* DYNACK_H */
 
                                if (bf == bf->bf_lastbf)
                                        ath_dynack_sample_tx_ts(sc->sc_ah,
                                                                bf->bf_mpdu,
-                                                               ts);
+                                                               ts, sta);
                        }
 
                        ath_tx_complete_buf(sc, bf, txq, &bf_head, sta, ts,
                        memcpy(info->control.rates, bf->rates,
                               sizeof(info->control.rates));
                        ath_tx_rc_status(sc, bf, ts, 1, txok ? 0 : 1, txok);
-                       ath_dynack_sample_tx_ts(sc->sc_ah, bf->bf_mpdu, ts);
+                       ath_dynack_sample_tx_ts(sc->sc_ah, bf->bf_mpdu, ts,
+                                               sta);
                }
                ath_tx_complete_buf(sc, bf, txq, bf_head, sta, ts, txok);
        } else