mac80211: fix AQL issues

- Remove bogus STA txq pending airtime underflow warning
- Improve tx airtime estimation for A-MPDU traffic

Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/kernel/mac80211/patches/subsys/305-mac80211-improve-AQL-tx-airtime-estimation.patch

@@ -0,0 +1,81 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Fri, 24 Jul 2020 20:25:07 +0200
+Subject: [PATCH] mac80211: improve AQL tx airtime estimation
+
+AQL does not take into account that most HT/VHT/HE traffic is A-MPDU aggregated.
+Because of that, the per-packet airtime overhead is vastly overestimated.
+Improve it by assuming an average aggregation length of 16 for non-legacy
+traffic if not using the VO AC queue.
+This should improve performance with high data rates, especially with multiple
+stations
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/airtime.c
++++ b/net/mac80211/airtime.c
+@@ -551,7 +551,7 @@ EXPORT_SYMBOL_GPL(ieee80211_calc_tx_airt
+ u32 ieee80211_calc_expected_tx_airtime(struct ieee80211_hw *hw,
+ 				       struct ieee80211_vif *vif,
+ 				       struct ieee80211_sta *pubsta,
+-				       int len)
++				       int len, bool ampdu)
+ {
+ 	struct ieee80211_supported_band *sband;
+ 	struct ieee80211_chanctx_conf *conf;
+@@ -572,10 +572,26 @@ u32 ieee80211_calc_expected_tx_airtime(s
+ 	if (pubsta) {
+ 		struct sta_info *sta = container_of(pubsta, struct sta_info,
+ 						    sta);
++		struct ieee80211_tx_rate *rate = &sta->tx_stats.last_rate;
++		u32 airtime;
+
+-		return ieee80211_calc_tx_airtime_rate(hw,
+-						      &sta->tx_stats.last_rate,
+-						      band, len);
++		if (!(rate->flags & (IEEE80211_TX_RC_VHT_MCS |
++				     IEEE80211_TX_RC_MCS)))
++			ampdu = false;
++
++		/*
++		 * Assume that HT/VHT transmission on any AC except VO will
++		 * use aggregation. Since we don't have reliable reporting
++		 * of aggregation length, assume an average of 16.
++		 * This will not be very accurate, but much better than simply
++		 * assuming un-aggregated tx.
++		 */
++		airtime = ieee80211_calc_tx_airtime_rate(hw, rate, band,
++							 ampdu ? len * 16 : len);
++		if (ampdu)
++			airtime /= 16;
++
++		return airtime;
+ 	}
+
+ 	if (!conf)
+--- a/net/mac80211/ieee80211_i.h
++++ b/net/mac80211/ieee80211_i.h
+@@ -2278,7 +2278,7 @@ extern const struct ethtool_ops ieee8021
+ u32 ieee80211_calc_expected_tx_airtime(struct ieee80211_hw *hw,
+ 				       struct ieee80211_vif *vif,
+ 				       struct ieee80211_sta *pubsta,
+-				       int len);
++				       int len, bool ampdu);
+ #ifdef CPTCFG_MAC80211_NOINLINE
+ #define debug_noinline noinline
+ #else
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -3694,10 +3694,11 @@ encap_out:
+
+ 	if (vif &&
+ 	    wiphy_ext_feature_isset(local->hw.wiphy, NL80211_EXT_FEATURE_AQL)) {
++		bool ampdu = txq->ac != IEEE80211_AC_VO;
+ 		u32 airtime;
+
+ 		airtime = ieee80211_calc_expected_tx_airtime(hw, vif, txq->sta,
+-							     skb->len);
++							     skb->len, ampdu);
+ 		if (airtime) {
+ 			airtime = ieee80211_info_set_tx_time_est(info, airtime);
+ 			ieee80211_sta_update_pending_airtime(local, tx.sta,

package/kernel/mac80211/patches/subsys/306-mac80211-remove-STA-txq-pending-airtime-underflow-wa.patch

@@ -0,0 +1,31 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 25 Jul 2020 10:42:30 +0200
+Subject: [PATCH] mac80211: remove STA txq pending airtime underflow
+ warning
+
+This warning can trigger if there is a mismatch between frames that were
+sent with the sta pointer set vs tx status frames reported for the sta address.
+
+This can happen due to race conditions on re-creating stations, or even
+in the case of .sta_add/remove being used instead of .sta_state, which can cause
+frames to be sent to a station that has not been uploaded yet.
+
+If there is an actual underflow issue, it should show up in the device airtime
+warning below, so it is better to remove this one.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/sta_info.c
++++ b/net/mac80211/sta_info.c
+@@ -1924,9 +1924,7 @@ void ieee80211_sta_update_pending_airtim
+ 	if (sta) {
+ 		tx_pending = atomic_sub_return(tx_airtime,
+ 					       &sta->airtime[ac].aql_tx_pending);
+-		if (WARN_ONCE(tx_pending < 0,
+-			      "STA %pM AC %d txq pending airtime underflow: %u, %u",
+-			      sta->addr, ac, tx_pending, tx_airtime))
++		if (tx_pending < 0)
+ 			atomic_cmpxchg(&sta->airtime[ac].aql_tx_pending,
+ 				       tx_pending, 0);
+ 	}