Index: madwifi-trunk-r3314/ath/if_ath.c
===================================================================
--- madwifi-trunk-r3314.orig/ath/if_ath.c	2008-02-20 21:59:04.037808900 +0100
+++ madwifi-trunk-r3314/ath/if_ath.c	2008-02-20 21:59:07.426001981 +0100
@@ -395,6 +395,7 @@
 static int maxvaps = -1;
 static int outdoor = -1;
 static int xchanmode = -1;
+static int beacon_cal = 1;
 
 static const char *hal_status_desc[] = {
 	"No error",
@@ -420,6 +421,7 @@
 };
 
 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,52))
+MODULE_PARM(beacon_cal, "i");
 MODULE_PARM(countrycode, "i");
 MODULE_PARM(maxvaps, "i");
 MODULE_PARM(outdoor, "i");
@@ -432,6 +434,7 @@
 MODULE_PARM(ratectl, "s");
 #else
 #include <linux/moduleparam.h>
+module_param(beacon_cal, int, 0600);
 module_param(countrycode, int, 0600);
 module_param(maxvaps, int, 0600);
 module_param(outdoor, int, 0600);
@@ -2595,7 +2598,8 @@
 		}
 		if (!sc->sc_invalid) {
 			del_timer_sync(&sc->sc_dfs_cac_timer);
-			del_timer_sync(&sc->sc_cal_ch);
+			if (!sc->sc_beacon_cal)
+				del_timer_sync(&sc->sc_cal_ch);
 		}
 		ath_draintxq(sc);
 		if (!sc->sc_invalid) {
@@ -2612,6 +2616,20 @@
 	return 0;
 }
 
+static void ath_set_beacon_cal(struct ath_softc *sc, int val)
+{
+	if (sc->sc_beacon_cal == !!val)
+		return;
+
+	if (val) {
+		del_timer_sync(&sc->sc_cal_ch);
+	} else {
+		sc->sc_cal_ch.expires = jiffies + (ath_calinterval * HZ);
+		add_timer(&sc->sc_cal_ch);
+	}
+	sc->sc_beacon_cal = !!val && beacon_cal;
+}
+
 /*
  * Stop the device, grabbing the top-level lock to protect
  * against concurrent entry through ath_init (which can happen
@@ -2737,6 +2755,12 @@
 	HAL_STATUS status;
 
 	/*
+	 * XXX: starting the calibration too early seems to lead to
+	 * problems with the beacons.
+	 */
+	sc->sc_lastcal = jiffies;
+
+	/*
 	 * Convert to a HAL channel description with the flags
 	 * constrained to reflect the current operating mode.
 	 */
@@ -5142,6 +5166,8 @@
 			"Invoking ath_hal_txstart with sc_bhalq: %d\n",
 			sc->sc_bhalq);
 		ath_hal_txstart(ah, sc->sc_bhalq);
+		if (sc->sc_beacon_cal && (jiffies > sc->sc_lastcal + (ath_calinterval * HZ)))
+			ath_calibrate((unsigned long) sc->sc_dev);
 
 		sc->sc_stats.ast_be_xmit++;		/* XXX per-VAP? */
 	}
@@ -5391,6 +5417,7 @@
 		ath_hal_beacontimers(ah, &bs);
 		sc->sc_imask |= HAL_INT_BMISS;
 		ath_hal_intrset(ah, sc->sc_imask);
+		ath_set_beacon_cal(sc, 0);
 	} else {
 		ath_hal_intrset(ah, 0);
 		if (reset_tsf)
@@ -5402,8 +5429,11 @@
 			 */
 			intval |= HAL_BEACON_ENA;
 			sc->sc_imask |= HAL_INT_SWBA;
+			ath_set_beacon_cal(sc, 1);
 			ath_beaconq_config(sc);
-		}
+		} else
+			ath_set_beacon_cal(sc, 0);
+
 #ifdef ATH_SUPERG_DYNTURBO
 		ath_beacon_dturbo_config(vap, intval &
 				~(HAL_BEACON_RESET_TSF | HAL_BEACON_ENA));
@@ -8864,6 +8894,9 @@
 			/* Enter DFS wait period */
 			mod_timer(&sc->sc_dfs_cac_timer,
 				jiffies + (sc->sc_dfs_cac_period * HZ));
+
+			/* This is a good time to start a calibration */
+			ath_set_beacon_cal(sc, 1);
 		}
 		/*
 		 * re configure beacons when it is a turbo mode switch.
@@ -8973,8 +9006,11 @@
 		sc->sc_curchan.channel, sc->sc_curchan.channelFlags,
 		isIQdone ? "done" : "not done");
 
-	sc->sc_cal_ch.expires = jiffies + (ath_calinterval * HZ);
-	add_timer(&sc->sc_cal_ch);
+	sc->sc_lastcal = jiffies;
+	if (!sc->sc_beacon_cal) {
+		sc->sc_cal_ch.expires = jiffies + (ath_calinterval * HZ);
+		add_timer(&sc->sc_cal_ch);
+	}
 }
 
 static void
@@ -9081,7 +9117,8 @@
 		ieee80211_state_name[vap->iv_state],
 		ieee80211_state_name[nstate]);
 
-	del_timer(&sc->sc_cal_ch);		/* periodic calibration timer */
+	if (!sc->sc_beacon_cal)
+		del_timer(&sc->sc_cal_ch);		/* periodic calibration timer */
 
 	ath_hal_setledstate(ah, leds[nstate]);	/* set LED */
 	netif_stop_queue(dev);			/* before we do anything else */
@@ -9306,7 +9343,8 @@
 				"VAP -> DFSWAIT_PENDING \n");
 			/* start calibration timer with a really small value 
 			 * 1/10 sec */
-			mod_timer(&sc->sc_cal_ch, jiffies + (HZ/10));
+			if (!sc->sc_beacon_cal)
+				mod_timer(&sc->sc_cal_ch, jiffies + (HZ/10));
 			/* wake the receiver */
 			netif_wake_queue(dev);
 			/* don't do the other usual stuff... */
@@ -9349,7 +9387,7 @@
 	error = avp->av_newstate(vap, nstate, arg);
 
 	/* Finally, start any timers. */
-	if (nstate == IEEE80211_S_RUN) {
+	if (nstate == IEEE80211_S_RUN && !sc->sc_beacon_cal) {
 		/* start periodic recalibration timer */
 		mod_timer(&sc->sc_cal_ch, jiffies + (ath_calinterval * HZ));
 	}
Index: madwifi-trunk-r3314/ath/if_athvar.h
===================================================================
--- madwifi-trunk-r3314.orig/ath/if_athvar.h	2008-02-20 21:58:38.148333545 +0100
+++ madwifi-trunk-r3314/ath/if_athvar.h	2008-02-20 21:59:07.426001981 +0100
@@ -778,6 +778,8 @@
 	struct ieee80211vap **sc_bslot;		/* beacon xmit slots */
 	int sc_bnext;				/* next slot for beacon xmit */
 
+	int sc_beacon_cal;			/* use beacon timer for calibration */
+	u_int64_t sc_lastcal;			/* last time the calibration was performed */
 	struct timer_list sc_cal_ch;		/* calibration timer */
 	HAL_NODE_STATS sc_halstats;		/* station-mode rssi stats */