ath9k: raise aggregation limit to 64k for HT IBSS

mac80211 adds stations in HT IBSS as soon as a frame comes by,
even if the HT capabilities are not known yet (they are often
received later, e.g. in beacons). So far, ampdu factor/density
are only calculated when the station is initially added.

This patch changes this to update ampdu factor/density settings
when starting a blockack session.

Using this patch, we had performance boosts from 60 to 150 MBit/s
between two 2x2 Atheros devices in 5 GHz HT IBSS mode.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 85f9ab4..e2e6958 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -19,7 +19,7 @@
 #include "ath9k.h"
 #include "btcoex.h"
 
-static u8 parse_mpdudensity(u8 mpdudensity)
+u8 ath9k_parse_mpdudensity(u8 mpdudensity)
 {
 	/*
 	 * 802.11n D2.0 defined values for "Minimum MPDU Start Spacing":
@@ -320,6 +320,7 @@
 			    struct ieee80211_vif *vif)
 {
 	struct ath_node *an;
+	u8 density;
 	an = (struct ath_node *)sta->drv_priv;
 
 #ifdef CONFIG_ATH9K_DEBUGFS
@@ -334,7 +335,8 @@
 		ath_tx_node_init(sc, an);
 		an->maxampdu = 1 << (IEEE80211_HT_MAX_AMPDU_FACTOR +
 				     sta->ht_cap.ampdu_factor);
-		an->mpdudensity = parse_mpdudensity(sta->ht_cap.ampdu_density);
+		density = ath9k_parse_mpdudensity(sta->ht_cap.ampdu_density);
+		an->mpdudensity = density;
 	}
 }