ath9k: Adjust tbtt delta properly

In a GO/STA setup, when we switch to the STA context,
the channel context timer is scheduled with a period of
half the beacon interval. If a beacon is received in
this duration, the timer is adjusted to accommodate
TSF sync done by the HW.

But, if the actual channel switch is delayed for some
reason, we end up rearming the timer every time a new
beacon is received. Avoid this by doing the adjustment
only once.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -381,6 +381,7 @@ enum ath_chanctx_state {
 
 struct ath_chanctx_sched {
 	bool beacon_pending;
+	bool beacon_adjust;
 	bool offchannel_pending;
 	bool wait_switch;
 	bool force_noa_update;

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

@@ -659,6 +659,7 @@ void ath_chanctx_event(struct ath_softc *sc, struct ieee80211_vif *vif,
 		sc->sched.beacon_miss = 0;
 
 		if (sc->sched.state == ATH_CHANCTX_STATE_FORCE_ACTIVE ||
+		    !sc->sched.beacon_adjust ||
 		    !sc->cur_chan->tsf_val)
 			break;
 
@@ -672,7 +673,7 @@ void ath_chanctx_event(struct ath_softc *sc, struct ieee80211_vif *vif,
 			ath9k_hw_get_tsf_offset(&sc->cur_chan->tsf_ts, NULL);
 		tsf_time += ath9k_hw_gettsf32(ah);
 
-
+		sc->sched.beacon_adjust = false;
 		ath_chanctx_setup_timer(sc, tsf_time);
 		break;
 	case ATH_CHANCTX_EVENT_AUTHORIZED:
@@ -717,6 +718,7 @@ void ath_chanctx_event(struct ath_softc *sc, struct ieee80211_vif *vif,
 
 		ath_chanctx_setup_timer(sc, tsf_time);
 		sc->sched.beacon_pending = true;
+		sc->sched.beacon_adjust = true;
 		break;
 	case ATH_CHANCTX_EVENT_ENABLE_MULTICHANNEL:
 		if (sc->cur_chan == &sc->offchannel.chan ||