ath9k: Dont update rate control for every AMPDU

Update the rate control only with the tx status of first
AMPDU of an aggregation. This patch fixes frequent drops
in throughput.

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath9k/rc.c

@@ -1413,7 +1413,8 @@ static void ath_tx_status(void *priv, struct ieee80211_supported_band *sband,
 	an = (struct ath_node *)sta->drv_priv;
 	final_ts_idx = tx_info_priv->tx.ts_rateindex;
 
-	if (!an || !priv_sta || !ieee80211_is_data(fc))
+	if (!an || !priv_sta || !ieee80211_is_data(fc) ||
+	    !tx_info_priv->update_rc)
 		goto exit;
 
 	if (tx_info_priv->tx.ts_status & ATH9K_TXERR_FILT)

drivers/net/wireless/ath9k/rc.h

@@ -188,6 +188,7 @@ struct ath_tx_info_priv {
 	struct ath_tx_status tx;
 	int n_frames;
 	int n_bad_frames;
+	bool update_rc;
 };
 
 #define ATH_TX_INFO_PRIV(tx_info) \

drivers/net/wireless/ath9k/xmit.c

@@ -950,6 +950,7 @@ static void ath_tx_rc_status(struct ath_buf *bf, struct ath_desc *ds, int nbad)
 	struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
 	struct ath_tx_info_priv *tx_info_priv = ATH_TX_INFO_PRIV(tx_info);
 
+	tx_info_priv->update_rc = false;
 	if (ds->ds_txstat.ts_status & ATH9K_TXERR_FILT)
 		tx_info->flags |= IEEE80211_TX_STAT_TX_FILTERED;
 
@@ -960,6 +961,7 @@ static void ath_tx_rc_status(struct ath_buf *bf, struct ath_desc *ds, int nbad)
 			       sizeof(tx_info_priv->tx));
 			tx_info_priv->n_frames = bf->bf_nframes;
 			tx_info_priv->n_bad_frames = nbad;
+			tx_info_priv->update_rc = true;
 		}
 	}
 }