mac80211: estimate expected throughput if not provided by driver/rc

Estimate the tx throughput based on the expected per-packet tx time.
This is useful for mesh implementations that rely on expected throughput,
e.g. 802.11s or batman-adv.

Signed-off-by: Felix Fietkau <[email protected]>

package/kernel/mac80211/patches/subsys/360-mac80211-factor-out-part-of-ieee80211_calc_expected_.patch

@@ -0,0 +1,140 @@
+From: Felix Fietkau <[email protected]>
+Date: Wed, 6 Aug 2025 10:49:54 +0200
+Subject: [PATCH] mac80211: factor out part of
+ ieee80211_calc_expected_tx_airtime
+
+Create ieee80211_rate_expected_tx_airtime helper function, which returns
+the expected tx airtime for a given rate and packet length in units of
+1024 usec, for more accuracy.
+
+Signed-off-by: Felix Fietkau <[email protected]>
+---
+
+--- a/net/mac80211/airtime.c
++++ b/net/mac80211/airtime.c
+@@ -685,7 +685,7 @@ static int ieee80211_fill_rx_status(stru
+ 	if (ieee80211_fill_rate_info(hw, stat, band, ri))
+ 		return 0;
+ 
+-	if (!ieee80211_rate_valid(rate))
++	if (!rate || !ieee80211_rate_valid(rate))
+ 		return -1;
+ 
+ 	if (rate->flags & IEEE80211_TX_RC_160_MHZ_WIDTH)
+@@ -753,6 +753,53 @@ u32 ieee80211_calc_tx_airtime(struct iee
+ }
+ EXPORT_SYMBOL_GPL(ieee80211_calc_tx_airtime);
+ 
++u32 ieee80211_rate_expected_tx_airtime(struct ieee80211_hw *hw,
++				       struct ieee80211_tx_rate *tx_rate,
++				       struct rate_info *ri,
++				       enum nl80211_band band,
++				       bool ampdu, int len)
++{
++	struct ieee80211_rx_status stat;
++	u32 duration, overhead;
++	u8 agg_shift;
++
++	if (ieee80211_fill_rx_status(&stat, hw, tx_rate, ri, band, len))
++		return 0;
++
++	if (stat.encoding == RX_ENC_LEGACY || !ampdu)
++		return ieee80211_calc_rx_airtime(hw, &stat, len) * 1024;
++
++	duration = ieee80211_get_rate_duration(hw, &stat, &overhead);
++
++	/*
++	 * 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 size based on the
++	 * tx rate.
++	 * This will not be very accurate, but much better than simply
++	 * assuming un-aggregated tx in all cases.
++	 */
++	if (duration > 400 * 1024) /* <= VHT20 MCS2 1S */
++		agg_shift = 1;
++	else if (duration > 250 * 1024) /* <= VHT20 MCS3 1S or MCS1 2S */
++		agg_shift = 2;
++	else if (duration > 150 * 1024) /* <= VHT20 MCS5 1S or MCS2 2S */
++		agg_shift = 3;
++	else if (duration > 70 * 1024) /* <= VHT20 MCS5 2S */
++		agg_shift = 4;
++	else if (stat.encoding != RX_ENC_HE ||
++		 duration > 20 * 1024) /* <= HE40 MCS6 2S */
++		agg_shift = 5;
++	else
++		agg_shift = 6;
++
++	duration *= len;
++	duration /= AVG_PKT_SIZE;
++	duration += (overhead * 1024 >> agg_shift);
++
++	return duration;
++}
++
+ u32 ieee80211_calc_expected_tx_airtime(struct ieee80211_hw *hw,
+ 				       struct ieee80211_vif *vif,
+ 				       struct ieee80211_sta *pubsta,
+@@ -775,45 +822,13 @@ u32 ieee80211_calc_expected_tx_airtime(s
+ 	if (pubsta) {
+ 		struct sta_info *sta = container_of(pubsta, struct sta_info,
+ 						    sta);
+-		struct ieee80211_rx_status stat;
+ 		struct ieee80211_tx_rate *tx_rate = &sta->deflink.tx_stats.last_rate;
+ 		struct rate_info *ri = &sta->deflink.tx_stats.last_rate_info;
+-		u32 duration, overhead;
+-		u8 agg_shift;
+-
+-		if (ieee80211_fill_rx_status(&stat, hw, tx_rate, ri, band, len))
+-			return 0;
+-
+-		if (stat.encoding == RX_ENC_LEGACY || !ampdu)
+-			return ieee80211_calc_rx_airtime(hw, &stat, len);
+-
+-		duration = ieee80211_get_rate_duration(hw, &stat, &overhead);
+-		/*
+-		 * 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 size based on the
+-		 * tx rate.
+-		 * This will not be very accurate, but much better than simply
+-		 * assuming un-aggregated tx in all cases.
+-		 */
+-		if (duration > 400 * 1024) /* <= VHT20 MCS2 1S */
+-			agg_shift = 1;
+-		else if (duration > 250 * 1024) /* <= VHT20 MCS3 1S or MCS1 2S */
+-			agg_shift = 2;
+-		else if (duration > 150 * 1024) /* <= VHT20 MCS5 1S or MCS2 2S */
+-			agg_shift = 3;
+-		else if (duration > 70 * 1024) /* <= VHT20 MCS5 2S */
+-			agg_shift = 4;
+-		else if (stat.encoding != RX_ENC_HE ||
+-			 duration > 20 * 1024) /* <= HE40 MCS6 2S */
+-			agg_shift = 5;
+-		else
+-			agg_shift = 6;
++		u32 duration;
+ 
+-		duration *= len;
+-		duration /= AVG_PKT_SIZE;
++		duration = ieee80211_rate_expected_tx_airtime(hw, tx_rate, ri,
++							      band, true, len);
+ 		duration /= 1024;
+-		duration += (overhead >> agg_shift);
+ 
+ 		return max_t(u32, duration, 4);
+ 	}
+--- a/net/mac80211/ieee80211_i.h
++++ b/net/mac80211/ieee80211_i.h
+@@ -2756,6 +2756,11 @@ u8 *ieee80211_get_bssid(struct ieee80211
+ 
+ extern const struct ethtool_ops ieee80211_ethtool_ops;
+ 
++u32 ieee80211_rate_expected_tx_airtime(struct ieee80211_hw *hw,
++				       struct ieee80211_tx_rate *tx_rate,
++				       struct rate_info *ri,
++				       enum nl80211_band band,
++				       bool ampdu, int len);
+ u32 ieee80211_calc_expected_tx_airtime(struct ieee80211_hw *hw,
+ 				       struct ieee80211_vif *vif,
+ 				       struct ieee80211_sta *pubsta,

package/kernel/mac80211/patches/subsys/361-mac80211-estimate-expected-throughput-if-not-provide.patch

@@ -0,0 +1,51 @@
+From: Felix Fietkau <[email protected]>
+Date: Wed, 6 Aug 2025 10:52:03 +0200
+Subject: [PATCH] mac80211: estimate expected throughput if not provided by
+ driver/rc
+
+Estimate the tx throughput based on the expected per-packet tx time.
+This is useful for mesh implementations that rely on expected throughput,
+e.g. 802.11s or batman-adv.
+
+Signed-off-by: Felix Fietkau <[email protected]>
+---
+
+--- a/net/mac80211/sta_info.c
++++ b/net/mac80211/sta_info.c
+@@ -2621,6 +2621,27 @@ static inline u64 sta_get_stats_bytes(st
+ 	return value;
+ }
+ 
++static u32 sta_estimate_expected_throughput(struct sta_info *sta,
++					    struct station_info *sinfo)
++{
++	struct ieee80211_sub_if_data *sdata = sta->sdata;
++	struct ieee80211_local *local = sdata->local;
++	struct rate_info *ri = &sinfo->txrate;
++	struct ieee80211_hw *hw = &local->hw;
++	struct ieee80211_chanctx_conf *conf;
++	u32 duration;
++	u8 band = 0;
++
++	conf = rcu_dereference(sdata->vif.bss_conf.chanctx_conf);
++	if (conf)
++			band = conf->def.chan->band;
++
++	duration = ieee80211_rate_expected_tx_airtime(hw, NULL, ri, band, true, 1024);
++	duration += duration >> 4; /* add assumed packet error rate of ~6% */
++
++	return ((1024 * USEC_PER_SEC) / duration) * 8;
++}
++
+ void sta_set_sinfo(struct sta_info *sta, struct station_info *sinfo,
+ 		   bool tidstats)
+ {
+@@ -2865,6 +2886,8 @@ void sta_set_sinfo(struct sta_info *sta,
+ 		sinfo->sta_flags.set |= BIT(NL80211_STA_FLAG_TDLS_PEER);
+ 
+ 	thr = sta_get_expected_throughput(sta);
++	if (!thr && (sinfo->filled & BIT_ULL(NL80211_STA_INFO_TX_BITRATE)))
++	    thr = sta_estimate_expected_throughput(sta, sinfo);
+ 
+ 	if (thr != 0) {
+ 		sinfo->filled |= BIT_ULL(NL80211_STA_INFO_EXPECTED_THROUGHPUT);