ath9k: optimize/fix ANI RSSI processing

ANI needs the RSSI average only in station mode, and only for tracking
the signal strength of beacons of the AP that it is connected to.
Adjust the code to track on the beacon RSSI, and store the average of that
in the ath_wiphy struct.
With these changes, we can get rid of this extra station lookup in the
rx path, which saves precious CPU cycles.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -270,7 +270,6 @@ struct ath_node {
 	struct ath_atx_ac ac[WME_NUM_AC];
 	u16 maxampdu;
 	u8 mpdudensity;
-	int last_rssi;
 };
 
 #define AGGR_CLEANUP         BIT(1)
@@ -662,6 +661,7 @@ struct ath_wiphy {
 	bool idle;
 	int chan_idx;
 	int chan_is_ht;
+	int last_rssi;
 };
 
 void ath9k_tasklet(unsigned long data);

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

@@ -703,6 +703,7 @@ int ath9k_init_device(u16 devid, struct ath_softc *sc, u16 subsysid,
 		    const struct ath_bus_ops *bus_ops)
 {
 	struct ieee80211_hw *hw = sc->hw;
+	struct ath_wiphy *aphy = hw->priv;
 	struct ath_common *common;
 	struct ath_hw *ah;
 	int error = 0;
@@ -752,6 +753,7 @@ int ath9k_init_device(u16 devid, struct ath_softc *sc, u16 subsysid,
 	INIT_WORK(&sc->chan_work, ath9k_wiphy_chan_work);
 	INIT_DELAYED_WORK(&sc->wiphy_work, ath9k_wiphy_work);
 	sc->wiphy_scheduler_int = msecs_to_jiffies(500);
+	aphy->last_rssi = ATH_RSSI_DUMMY_MARKER;
 
 	ath_init_leds(sc);
 	ath_start_rfkill_poll(sc);

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

@@ -562,7 +562,6 @@ static void ath_node_attach(struct ath_softc *sc, struct ieee80211_sta *sta)
 		an->maxampdu = 1 << (IEEE80211_HT_MAX_AMPDU_FACTOR +
 				     sta->ht_cap.ampdu_factor);
 		an->mpdudensity = parse_mpdudensity(sta->ht_cap.ampdu_density);
-		an->last_rssi = ATH_RSSI_DUMMY_MARKER;
 	}
 }
 
@@ -831,9 +830,11 @@ static u32 ath_get_extchanmode(struct ath_softc *sc,
 }
 
 static void ath9k_bss_assoc_info(struct ath_softc *sc,
+				 struct ieee80211_hw *hw,
 				 struct ieee80211_vif *vif,
 				 struct ieee80211_bss_conf *bss_conf)
 {
+	struct ath_wiphy *aphy = hw->priv;
 	struct ath_hw *ah = sc->sc_ah;
 	struct ath_common *common = ath9k_hw_common(ah);
 
@@ -857,6 +858,7 @@ static void ath9k_bss_assoc_info(struct ath_softc *sc,
 		ath_beacon_config(sc, vif);
 
 		/* Reset rssi stats */
+		aphy->last_rssi = ATH_RSSI_DUMMY_MARKER;
 		sc->sc_ah->stats.avgbrssi = ATH_RSSI_DUMMY_MARKER;
 
 		sc->sc_flags |= SC_OP_ANI_RUN;
@@ -1998,7 +2000,7 @@ static void ath9k_bss_info_changed(struct ieee80211_hw *hw,
 	if (changed & BSS_CHANGED_ASSOC) {
 		ath_print(common, ATH_DBG_CONFIG, "BSS Changed ASSOC %d\n",
 			bss_conf->assoc);
-		ath9k_bss_assoc_info(sc, vif, bss_conf);
+		ath9k_bss_assoc_info(sc, hw, vif, bss_conf);
 	}
 
 	mutex_unlock(&sc->mutex);

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

@@ -962,36 +962,23 @@ static void ath9k_process_rssi(struct ath_common *common,
 			       struct ieee80211_hdr *hdr,
 			       struct ath_rx_status *rx_stats)
 {
+	struct ath_wiphy *aphy = hw->priv;
 	struct ath_hw *ah = common->ah;
-	struct ieee80211_sta *sta;
-	struct ath_node *an;
-	int last_rssi = ATH_RSSI_DUMMY_MARKER;
+	int last_rssi;
 	__le16 fc;
 
+	if (ah->opmode != NL80211_IFTYPE_STATION)
+		return;
+
 	fc = hdr->frame_control;
+	if (!ieee80211_is_beacon(fc) ||
+	    compare_ether_addr(hdr->addr3, common->curbssid))
+		return;
 
-	rcu_read_lock();
-	/*
-	 * XXX: use ieee80211_find_sta! This requires quite a bit of work
-	 * under the current ath9k virtual wiphy implementation as we have
-	 * no way of tying a vif to wiphy. Typically vifs are attached to
-	 * at least one sdata of a wiphy on mac80211 but with ath9k virtual
-	 * wiphy you'd have to iterate over every wiphy and each sdata.
-	 */
-	if (is_multicast_ether_addr(hdr->addr1))
-		sta = ieee80211_find_sta_by_ifaddr(hw, hdr->addr2, NULL);
-	else
-		sta = ieee80211_find_sta_by_ifaddr(hw, hdr->addr2, hdr->addr1);
-
-	if (sta) {
-		an = (struct ath_node *) sta->drv_priv;
-		if (rx_stats->rs_rssi != ATH9K_RSSI_BAD &&
-		   !rx_stats->rs_moreaggr)
-			ATH_RSSI_LPF(an->last_rssi, rx_stats->rs_rssi);
-		last_rssi = an->last_rssi;
-	}
-	rcu_read_unlock();
+	if (rx_stats->rs_rssi != ATH9K_RSSI_BAD && !rx_stats->rs_moreaggr)
+		ATH_RSSI_LPF(aphy->last_rssi, rx_stats->rs_rssi);
 
+	last_rssi = aphy->last_rssi;
 	if (likely(last_rssi != ATH_RSSI_DUMMY_MARKER))
 		rx_stats->rs_rssi = ATH_EP_RND(last_rssi,
 					      ATH_RSSI_EP_MULTIPLIER);
@@ -999,8 +986,7 @@ static void ath9k_process_rssi(struct ath_common *common,
 		rx_stats->rs_rssi = 0;
 
 	/* Update Beacon RSSI, this is used by ANI. */
-	if (ieee80211_is_beacon(fc))
-		ah->stats.avgbrssi = rx_stats->rs_rssi;
+	ah->stats.avgbrssi = rx_stats->rs_rssi;
 }
 
 /*

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

@@ -107,6 +107,7 @@ int ath9k_wiphy_add(struct ath_softc *sc)
 	aphy->sc = sc;
 	aphy->hw = hw;
 	sc->sec_wiphy[i] = aphy;
+	aphy->last_rssi = ATH_RSSI_DUMMY_MARKER;
 	spin_unlock_bh(&sc->wiphy_lock);
 
 	memcpy(addr, common->macaddr, ETH_ALEN);