mac80211: remove tx status call to ieee80211_sta_register_airtime

All drivers using airtime fairness are calling ieee80211_sta_register_airtime
directly, now they must. Document this as well.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20200908123702.88454-8-nbd@nbd.name
[johannes: update the documentation to suit]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -1002,7 +1002,8 @@ ieee80211_rate_get_vht_nss(const struct ieee80211_tx_rate *rate)
  * @status.ampdu_ack_len: AMPDU ack length
  * @status.ampdu_len: AMPDU length
  * @status.antenna: (legacy, kept only for iwlegacy)
- * @status.tx_time: airtime consumed for transmission
+ * @status.tx_time: airtime consumed for transmission; note this is only
+ *	used for WMM AC, not for airtime fairness
  * @status.is_valid_ack_signal: ACK signal is valid
  * @status.status_driver_data: driver use area
  * @ack: union part for pure ACK data
@@ -5676,7 +5677,7 @@ void ieee80211_send_eosp_nullfunc(struct ieee80211_sta *pubsta, int tid);
 /**
  * ieee80211_sta_register_airtime - register airtime usage for a sta/tid
  *
- * Register airtime usage for a given sta on a given tid. The driver can call
+ * Register airtime usage for a given sta on a given tid. The driver must call
  * this function to notify mac80211 that a station used a certain amount of
  * airtime. This information will be used by the TXQ scheduler to schedule
  * stations in a way that ensures airtime fairness.

net/mac80211/status.c

@@ -988,12 +988,6 @@ static void __ieee80211_tx_status(struct ieee80211_hw *hw,
 			ieee80211_sta_tx_notify(sta->sdata, (void *) skb->data,
 						acked, info->status.tx_time);
 
-		if (info->status.tx_time &&
-		    wiphy_ext_feature_isset(local->hw.wiphy,
-					    NL80211_EXT_FEATURE_AIRTIME_FAIRNESS))
-			ieee80211_sta_register_airtime(&sta->sta, tid,
-						       info->status.tx_time, 0);
-
 		if ((tx_time_est = ieee80211_info_get_tx_time_est(info)) > 0) {
 			/* Do this here to avoid the expensive lookup of the sta
 			 * in ieee80211_report_used_skb().