From: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Date: Fri, 2 Nov 2018 21:49:58 +0100
Subject: [PATCH] ath9k: dynack: make ewma estimation faster

In order to make propagation time estimation faster,
use current sample as ewma output value during 'late ack'
tracking

Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
---

--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -274,7 +274,7 @@ struct ath_node {
 #endif
 	u8 key_idx[4];
 
-	u32 ackto;
+	int ackto;
 	struct list_head list;
 };
 
--- a/drivers/net/wireless/ath/ath9k/dynack.c
+++ b/drivers/net/wireless/ath/ath9k/dynack.c
@@ -29,9 +29,13 @@
  * 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;
 }
 
 /**
@@ -82,10 +86,10 @@ static inline bool ath_dynack_bssidmask(
  */
 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)
@@ -144,7 +148,8 @@ static void ath_dynack_compute_to(struct
 					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;
@@ -166,10 +171,12 @@ static void ath_dynack_compute_to(struct
  * @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;
@@ -191,9 +198,16 @@ void ath_dynack_sample_tx_ts(struct ath_
 		    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;
 		}
 
--- a/drivers/net/wireless/ath/ath9k/dynack.h
+++ b/drivers/net/wireless/ath/ath9k/dynack.h
@@ -86,7 +86,8 @@ void ath_dynack_node_deinit(struct ath_h
 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,
@@ -97,7 +98,8 @@ static inline void ath_dynack_sample_ack
 					    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 */
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -629,7 +629,7 @@ static void ath_tx_complete_aggr(struct
 				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,
@@ -773,7 +773,8 @@ static void ath_tx_process_buffer(struct
 			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