mac80211: Extend the rate control API with an update callback

The AP can switch dynamically between 20/40 Mhz channel width,
in which case we switch the local operating channel, but the
rate control algorithm is not notified. This patch adds a new callback
to indicate such changes to the RC algorithm.

Currently, HT channel width change is notified, but this callback
can be used to indicate any new requirements that might come up later on.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/ht.c b/net/mac80211/ht.c
index 69b6e9a..4e3c72f 100644
--- a/net/mac80211/ht.c
+++ b/net/mac80211/ht.c
@@ -17,6 +17,7 @@
 #include <net/wireless.h>
 #include <net/mac80211.h>
 #include "ieee80211_i.h"
+#include "rate.h"
 
 void ieee80211_ht_cap_ie_to_sta_ht_cap(struct ieee80211_supported_band *sband,
 				       struct ieee80211_ht_cap *ht_cap_ie,
@@ -93,7 +94,9 @@
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_supported_band *sband;
+	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 	struct ieee80211_bss_ht_conf ht;
+	struct sta_info *sta;
 	u32 changed = 0;
 	bool enable_ht = true, ht_changed;
 	enum nl80211_channel_type channel_type = NL80211_CHAN_NO_HT;
@@ -136,6 +139,16 @@
 	if (ht_changed) {
                 /* channel_type change automatically detected */
 		ieee80211_hw_config(local, 0);
+
+		rcu_read_lock();
+
+		sta = sta_info_get(local, ifmgd->bssid);
+		if (sta)
+			rate_control_rate_update(local, sband, sta,
+						 IEEE80211_RC_HT_CHANGED);
+
+		rcu_read_unlock();
+
         }
 
 	/* disable HT */