ath9k: Fix max AMPDU size calculation

The maximum A-MPDU size is calculated in ath_tx_aggr_start(),
so there is no need to do it in node_attach() too. Also, make
sure that the correct size is calculated as described in
8.4.2.58.3.
Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/main.c

@@ -427,12 +427,6 @@ static void ath_node_attach(struct ath_softc *sc, struct ieee80211_sta *sta,
 	an->vif = vif;
 
 	ath_tx_node_init(sc, an);
-
-	if (sta->ht_cap.ht_supported) {
-		an->maxampdu = 1 << (IEEE80211_HT_MAX_AMPDU_FACTOR +
-				     sta->ht_cap.ampdu_factor);
-		an->mpdudensity = ath9k_parse_mpdudensity(sta->ht_cap.ampdu_density);
-	}
 }
 
 static void ath_node_detach(struct ath_softc *sc, struct ieee80211_sta *sta)

drivers/net/wireless/ath/ath9k/xmit.c

@@ -774,11 +774,6 @@ static u32 ath_lookup_rate(struct ath_softc *sc, struct ath_buf *bf,
 	if (bt_aggr_limit)
 		aggr_limit = bt_aggr_limit;
 
-	/*
-	 * h/w can accept aggregates up to 16 bit lengths (65535).
-	 * The IE, however can hold up to 65536, which shows up here
-	 * as zero. Ignore 65536 since we  are constrained by hw.
-	 */
 	if (tid->an->maxampdu)
 		aggr_limit = min(aggr_limit, tid->an->maxampdu);
 
@@ -1399,8 +1394,8 @@ int ath_tx_aggr_start(struct ath_softc *sc, struct ieee80211_sta *sta,
 	 * has already been added.
 	 */
 	if (sta->ht_cap.ht_supported) {
-		an->maxampdu = 1 << (IEEE80211_HT_MAX_AMPDU_FACTOR +
-				     sta->ht_cap.ampdu_factor);
+		an->maxampdu = (1 << (IEEE80211_HT_MAX_AMPDU_FACTOR +
+				      sta->ht_cap.ampdu_factor)) - 1;
 		density = ath9k_parse_mpdudensity(sta->ht_cap.ampdu_density);
 		an->mpdudensity = density;
 	}