freifunkist-firmware/package/mac80211/patches/542-ath9k_bstuck_nf_calibrate.patch

--- a/drivers/net/wireless/ath/ath9k/beacon.c
+++ b/drivers/net/wireless/ath/ath9k/beacon.c
@@ -362,6 +362,7 @@ void ath_beacon_tasklet(unsigned long da
 			ath_print(common, ATH_DBG_BSTUCK,
 				  "missed %u consecutive beacons\n",
 				  sc->beacon.bmisscnt);
+			ath9k_hw_bstuck_nfcal(ah);
 		} else if (sc->beacon.bmisscnt >= BSTUCK_THRESH) {
 			ath_print(common, ATH_DBG_BSTUCK,
 				  "beacon is officially stuck\n");
--- a/drivers/net/wireless/ath/ath9k/calib.c
+++ b/drivers/net/wireless/ath/ath9k/calib.c
@@ -65,12 +65,16 @@ static s16 ath9k_hw_get_default_nf(struc
 
 
 static void ath9k_hw_update_nfcal_hist_buffer(struct ath_hw *ah,
-					      struct ath9k_nfcal_hist *h,
+					      struct ath9k_hw_cal_data *cal,
 					      int16_t *nfarray)
 {
+	struct ath_common *common = ath9k_hw_common(ah);
 	struct ath_nf_limits *limit;
+	struct ath9k_nfcal_hist *h;
+	bool high_nf_mid = false;
 	int i;
 
+	h = cal->nfCalHist;
 	limit = ath9k_hw_get_nf_limits(ah, ah->curchan);
 
 	for (i = 0; i < NUM_NF_READINGS; i++) {
@@ -87,9 +91,38 @@ static void ath9k_hw_update_nfcal_hist_b
 				ath9k_hw_get_nf_hist_mid(h[i].nfCalBuffer);
 		}
 
-		if (h[i].privNF > limit->max)
-			h[i].privNF = limit->max;
+		if (!h[i].privNF)
+			continue;
+
+		if (h[i].privNF > limit->max) {
+			high_nf_mid = true;
+
+			ath_print(common, ATH_DBG_CALIBRATE,
+				  "NFmid[%d] (%d) > MAX (%d), %s\n",
+				  i, h[i].privNF, limit->max,
+				  (cal->nfcal_interference ?
+				   "not corrected (due to interference)" :
+				   "correcting to MAX"));
+
+			/*
+			 * Normally we limit the average noise floor by the
+			 * hardware specific maximum here. However if we have
+			 * encountered stuck beacons because of interference,
+			 * we bypass this limit here in order to better deal
+			 * with our environment.
+			 */
+			if (!cal->nfcal_interference)
+				h[i].privNF = limit->max;
+		}
 	}
+
+	/*
+	 * If the noise floor seems normal for all chains, assume that
+	 * there is no significant interference in the environment anymore.
+	 * Re-enable the enforcement of the NF maximum again.
+	 */
+	if (!high_nf_mid)
+		cal->nfcal_interference = false;
 }
 
 static bool ath9k_hw_get_nf_thresh(struct ath_hw *ah,
@@ -339,7 +372,7 @@ bool ath9k_hw_getnf(struct ath_hw *ah, s
 
 	h = caldata->nfCalHist;
 	caldata->nfcal_pending = false;
-	ath9k_hw_update_nfcal_hist_buffer(ah, h, nfarray);
+	ath9k_hw_update_nfcal_hist_buffer(ah, caldata, nfarray);
 	caldata->rawNoiseFloor = h[0].privNF;
 	return true;
 }
@@ -374,3 +407,28 @@ s16 ath9k_hw_getchan_noise(struct ath_hw
 	return ah->caldata->rawNoiseFloor;
 }
 EXPORT_SYMBOL(ath9k_hw_getchan_noise);
+
+void ath9k_hw_bstuck_nfcal(struct ath_hw *ah)
+{
+	struct ath9k_hw_cal_data *caldata = ah->caldata;
+
+	if (unlikely(!caldata))
+		return;
+
+	/*
+	 * If beacons are stuck, the most likely cause is interference.
+	 * Triggering a noise floor calibration at this point helps the
+	 * hardware adapt to a noisy environment much faster.
+	 * To ensure that we recover from stuck beacons quickly, let
+	 * the baseband update the internal NF value itself, similar to
+	 * what is being done after a full reset.
+	 */
+	if (!caldata->nfcal_pending)
+		ath9k_hw_start_nfcal(ah, true);
+	else if (!(REG_READ(ah, AR_PHY_AGC_CONTROL) & AR_PHY_AGC_CONTROL_NF))
+		ath9k_hw_getnf(ah, ah->curchan);
+
+	caldata->nfcal_interference = true;
+}
+EXPORT_SYMBOL(ath9k_hw_bstuck_nfcal);
+
--- a/drivers/net/wireless/ath/ath9k/calib.h
+++ b/drivers/net/wireless/ath/ath9k/calib.h
@@ -113,6 +113,7 @@ void ath9k_hw_loadnf(struct ath_hw *ah, 
 bool ath9k_hw_getnf(struct ath_hw *ah, struct ath9k_channel *chan);
 void ath9k_init_nfcal_hist_buffer(struct ath_hw *ah,
 				  struct ath9k_channel *chan);
+void ath9k_hw_bstuck_nfcal(struct ath_hw *ah);
 s16 ath9k_hw_getchan_noise(struct ath_hw *ah, struct ath9k_channel *chan);
 void ath9k_hw_reset_calibration(struct ath_hw *ah,
 				struct ath9k_cal_list *currCal);
--- a/drivers/net/wireless/ath/ath9k/hw.h
+++ b/drivers/net/wireless/ath/ath9k/hw.h
@@ -355,6 +355,7 @@ struct ath9k_hw_cal_data {
 	int16_t rawNoiseFloor;
 	bool paprd_done;
 	bool nfcal_pending;
+	bool nfcal_interference;
 	u16 small_signal_gain[AR9300_MAX_CHAINS];
 	u32 pa_table[AR9300_MAX_CHAINS][PAPRD_TABLE_SZ];
 	struct ath9k_nfcal_hist nfCalHist[NUM_NF_READINGS];