ath5k: run NF calibration only every 60 seconds

Since NF calibration interferes with TX and RX and also has been the cause of
other problems (when it's run concurrently with ath5k_reset) we want to run it
less often - every 60 seconds for now.
Signed-off-by: Bruno Randolf <br1@einfach.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath5k/ath5k.h

@@ -204,6 +204,7 @@
 #define AR5K_TUNE_TPC_TXPOWER			false
 #define ATH5K_TUNE_CALIBRATION_INTERVAL_FULL    10000   /* 10 sec */
 #define ATH5K_TUNE_CALIBRATION_INTERVAL_ANI	1000	/* 1 sec */
+#define ATH5K_TUNE_CALIBRATION_INTERVAL_NF	60000	/* 60 sec */
 
 #define AR5K_INIT_CARR_SENSE_EN			1
 
@@ -1118,6 +1119,7 @@ struct ath5k_hw {
 	/* Calibration timestamp */
 	unsigned long		ah_cal_next_full;
 	unsigned long		ah_cal_next_ani;
+	unsigned long		ah_cal_next_nf;
 
 	/* Calibration mask */
 	u8			ah_cal_mask;

drivers/net/wireless/ath/ath5k/base.c

@@ -2803,14 +2803,16 @@ ath5k_tasklet_calibrate(unsigned long data)
 			ieee80211_frequency_to_channel(
 				sc->curchan->center_freq));
 
-	/* TODO: We don't need to run noise floor calibration as often
-	 * as I/Q calibration.*/
-
 	/* Noise floor calibration interrupts rx/tx path while I/Q calibration
-	 * doesn't. Stop queues so that calibration doesn't interfere with tx */
-	ieee80211_stop_queues(sc->hw);
-	ath5k_hw_update_noise_floor(ah);
-	ieee80211_wake_queues(sc->hw);
+	 * doesn't. We stop the queues so that calibration doesn't interfere
+	 * with TX and don't run it as often */
+	if (time_is_before_eq_jiffies(ah->ah_cal_next_nf)) {
+		ah->ah_cal_next_nf = jiffies +
+			msecs_to_jiffies(ATH5K_TUNE_CALIBRATION_INTERVAL_NF);
+		ieee80211_stop_queues(sc->hw);
+		ath5k_hw_update_noise_floor(ah);
+		ieee80211_wake_queues(sc->hw);
+	}
 
 	ah->ah_cal_mask &= ~AR5K_CALIBRATION_FULL;
 }
@@ -2931,6 +2933,8 @@ ath5k_reset(struct ath5k_softc *sc, struct ieee80211_channel *chan)
 
 	ah->ah_cal_next_full = jiffies;
 	ah->ah_cal_next_ani = jiffies;
+	ah->ah_cal_next_nf = jiffies;
+
 	/*
 	 * Change channels and update the h/w rate map if we're switching;
 	 * e.g. 11a to 11b/g.