diff --git a/drivers/net/wireless/zd1211rw/zd_mac.c b/drivers/net/wireless/zd1211rw/zd_mac.c
index a3c7e8f..d4b4036 100644
--- a/drivers/net/wireless/zd1211rw/zd_mac.c
+++ b/drivers/net/wireless/zd1211rw/zd_mac.c
@@ -138,6 +138,9 @@ static const struct ieee80211_channel zd_channels[] = {
 static void housekeeping_init(struct zd_mac *mac);
 static void housekeeping_enable(struct zd_mac *mac);
 static void housekeeping_disable(struct zd_mac *mac);
+static void beacon_init(struct zd_mac *mac);
+static void beacon_enable(struct zd_mac *mac);
+static void beacon_disable(struct zd_mac *mac);
 
 static int zd_reg2alpha2(u8 regdomain, char *alpha2)
 {
@@ -295,6 +298,8 @@ static int zd_op_start(struct ieee80211_hw *hw)
 		goto disable_rxtx;
 
 	housekeeping_enable(mac);
+	beacon_enable(mac);
+	set_bit(ZD_DEVICE_RUNNING, &mac->flags);
 	return 0;
 disable_rxtx:
 	zd_chip_disable_rxtx(chip);
@@ -313,12 +318,15 @@ static void zd_op_stop(struct ieee80211_hw *hw)
 	struct sk_buff *skb;
 	struct sk_buff_head *ack_wait_queue = &mac->ack_wait_queue;
 
+	clear_bit(ZD_DEVICE_RUNNING, &mac->flags);
+
 	/* The order here deliberately is a little different from the open()
 	 * method, since we need to make sure there is no opportunity for RX
 	 * frames to be processed by mac80211 after we have stopped it.
 	 */
 
 	zd_chip_disable_rxtx(chip);
+	beacon_disable(mac);
 	housekeeping_disable(mac);
 	flush_workqueue(zd_workqueue);
 
@@ -594,64 +602,99 @@ static void cs_set_control(struct zd_mac *mac, struct zd_ctrlset *cs,
 static int zd_mac_config_beacon(struct ieee80211_hw *hw, struct sk_buff *beacon)
 {
 	struct zd_mac *mac = zd_hw_mac(hw);
-	int r;
+	int r, ret;
 	u32 tmp, j = 0;
 	/* 4 more bytes for tail CRC */
 	u32 full_len = beacon->len + 4;
+	unsigned long end_jiffies, message_jiffies;
+
+	mutex_lock(&mac->chip.mutex);
 
-	r = zd_iowrite32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, 0);
+	r = zd_iowrite32_locked(&mac->chip, 0, CR_BCN_FIFO_SEMAPHORE);
 	if (r < 0)
-		return r;
-	r = zd_ioread32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, &tmp);
+		goto out;
+	r = zd_ioread32_locked(&mac->chip, &tmp, CR_BCN_FIFO_SEMAPHORE);
 	if (r < 0)
-		return r;
+		goto release_sema;
 
+	end_jiffies = jiffies + HZ / 2; /*~500ms*/
+	message_jiffies = jiffies + HZ / 10; /*~100ms*/
 	while (tmp & 0x2) {
-		r = zd_ioread32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, &tmp);
+		r = zd_ioread32_locked(&mac->chip, &tmp, CR_BCN_FIFO_SEMAPHORE);
 		if (r < 0)
-			return r;
-		if ((++j % 100) == 0) {
-			printk(KERN_ERR "CR_BCN_FIFO_SEMAPHORE not ready\n");
-			if (j >= 500)  {
-				printk(KERN_ERR "Giving up beacon config.\n");
-				return -ETIMEDOUT;
+			goto release_sema;
+		if (time_is_before_eq_jiffies(message_jiffies)) {
+			message_jiffies = jiffies + HZ / 10;
+			dev_err(zd_mac_dev(mac),
+					"CR_BCN_FIFO_SEMAPHORE not ready\n");
+			if (time_is_before_eq_jiffies(end_jiffies))  {
+				dev_err(zd_mac_dev(mac),
+						"Giving up beacon config.\n");
+				r = -ETIMEDOUT;
+				goto release_sema;
 			}
 		}
-		msleep(1);
+		msleep(20);
 	}
 
-	r = zd_iowrite32(&mac->chip, CR_BCN_FIFO, full_len - 1);
+	r = zd_iowrite32_locked(&mac->chip, full_len - 1, CR_BCN_FIFO);
 	if (r < 0)
-		return r;
+		goto release_sema;
 	if (zd_chip_is_zd1211b(&mac->chip)) {
-		r = zd_iowrite32(&mac->chip, CR_BCN_LENGTH, full_len - 1);
+		r = zd_iowrite32_locked(&mac->chip, full_len - 1,
+					CR_BCN_LENGTH);
 		if (r < 0)
-			return r;
+			goto release_sema;
 	}
 
 	for (j = 0 ; j < beacon->len; j++) {
-		r = zd_iowrite32(&mac->chip, CR_BCN_FIFO,
-				*((u8 *)(beacon->data + j)));
+		r = zd_iowrite32_locked(&mac->chip, *((u8 *)(beacon->data + j)),
+					CR_BCN_FIFO);
 		if (r < 0)
-			return r;
+			goto release_sema;
 	}
 
 	for (j = 0; j < 4; j++) {
-		r = zd_iowrite32(&mac->chip, CR_BCN_FIFO, 0x0);
+		r = zd_iowrite32_locked(&mac->chip, 0x0, CR_BCN_FIFO);
 		if (r < 0)
-			return r;
+			goto release_sema;
 	}
 
-	r = zd_iowrite32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, 1);
-	if (r < 0)
-		return r;
+release_sema:
+	/*
+	 * Try very hard to release device beacon semaphore, as otherwise
+	 * device/driver can be left in unusable state.
+	 */
+	end_jiffies = jiffies + HZ / 2; /*~500ms*/
+	ret = zd_iowrite32_locked(&mac->chip, 1, CR_BCN_FIFO_SEMAPHORE);
+	while (ret < 0) {
+		if (time_is_before_eq_jiffies(end_jiffies)) {
+			ret = -ETIMEDOUT;
+			break;
+		}
+
+		msleep(20);
+		ret = zd_iowrite32_locked(&mac->chip, 1, CR_BCN_FIFO_SEMAPHORE);
+	}
+
+	if (ret < 0)
+		dev_err(zd_mac_dev(mac), "Could not release "
+					 "CR_BCN_FIFO_SEMAPHORE!\n");
+	if (r < 0 || ret < 0) {
+		if (r >= 0)
+			r = ret;
+		goto out;
+	}
 
 	/* 802.11b/g 2.4G CCK 1Mb
 	 * 802.11a, not yet implemented, uses different values (see GPL vendor
 	 * driver)
 	 */
-	return zd_iowrite32(&mac->chip, CR_BCN_PLCP_CFG, 0x00000400 |
-			(full_len << 19));
+	r = zd_iowrite32_locked(&mac->chip, 0x00000400 | (full_len << 19),
+				CR_BCN_PLCP_CFG);
+out:
+	mutex_unlock(&mac->chip.mutex);
+	return r;
 }
 
 static void create_tx_desc_seq(struct zd_mac *mac, struct ieee80211_hdr *hdr,
@@ -962,6 +1005,8 @@ static void zd_beacon_done(struct zd_mac *mac)
 {
 	struct sk_buff *skb, *beacon;
 
+	if (!test_bit(ZD_DEVICE_RUNNING, &mac->flags))
+		return;
 	if (!mac->vif || mac->vif->type != NL80211_IFTYPE_AP)
 		return;
 
@@ -979,11 +1024,14 @@ static void zd_beacon_done(struct zd_mac *mac)
 	 * Fetch next beacon so that tim_count is updated.
 	 */
 	beacon = ieee80211_beacon_get(mac->hw, mac->vif);
-	if (!beacon)
-		return;
+	if (beacon) {
+		zd_mac_config_beacon(mac->hw, beacon);
+		kfree_skb(beacon);
+	}
 
-	zd_mac_config_beacon(mac->hw, beacon);
-	kfree_skb(beacon);
+	spin_lock_irq(&mac->lock);
+	mac->beacon.last_update = jiffies;
+	spin_unlock_irq(&mac->lock);
 }
 
 static void zd_process_intr(struct work_struct *work)
@@ -1098,7 +1146,9 @@ static void zd_op_bss_info_changed(struct ieee80211_hw *hw,
 			struct sk_buff *beacon = ieee80211_beacon_get(hw, vif);
 
 			if (beacon) {
+				zd_chip_disable_hwint(&mac->chip);
 				zd_mac_config_beacon(hw, beacon);
+				zd_chip_enable_hwint(&mac->chip);
 				kfree_skb(beacon);
 			}
 		}
@@ -1112,6 +1162,12 @@ static void zd_op_bss_info_changed(struct ieee80211_hw *hw,
 				interval = bss_conf->beacon_int;
 			}
 
+			spin_lock_irq(&mac->lock);
+			mac->beacon.period = period;
+			mac->beacon.interval = interval;
+			mac->beacon.last_update = jiffies;
+			spin_unlock_irq(&mac->lock);
+
 			zd_set_beacon_interval(&mac->chip, interval, period,
 					       mac->type);
 		}
@@ -1205,12 +1261,83 @@ struct ieee80211_hw *zd_mac_alloc_hw(struct usb_interface *intf)
 
 	zd_chip_init(&mac->chip, hw, intf);
 	housekeeping_init(mac);
+	beacon_init(mac);
 	INIT_WORK(&mac->process_intr, zd_process_intr);
 
 	SET_IEEE80211_DEV(hw, &intf->dev);
 	return hw;
 }
 
+#define BEACON_WATCHDOG_DELAY round_jiffies_relative(HZ)
+
+static void beacon_watchdog_handler(struct work_struct *work)
+{
+	struct zd_mac *mac =
+		container_of(work, struct zd_mac, beacon.watchdog_work.work);
+	struct sk_buff *beacon;
+	unsigned long timeout;
+	int interval, period;
+
+	if (!test_bit(ZD_DEVICE_RUNNING, &mac->flags))
+		goto rearm;
+	if (mac->type != NL80211_IFTYPE_AP || !mac->vif)
+		goto rearm;
+
+	spin_lock_irq(&mac->lock);
+	interval = mac->beacon.interval;
+	period = mac->beacon.period;
+	timeout = mac->beacon.last_update + msecs_to_jiffies(interval) + HZ;
+	spin_unlock_irq(&mac->lock);
+
+	if (interval > 0 && time_is_before_jiffies(timeout)) {
+		dev_dbg_f(zd_mac_dev(mac), "beacon interrupt stalled, "
+					   "restarting. "
+					   "(interval: %d, dtim: %d)\n",
+					   interval, period);
+
+		zd_chip_disable_hwint(&mac->chip);
+
+		beacon = ieee80211_beacon_get(mac->hw, mac->vif);
+		if (beacon) {
+			zd_mac_config_beacon(mac->hw, beacon);
+			kfree_skb(beacon);
+		}
+
+		zd_set_beacon_interval(&mac->chip, interval, period, mac->type);
+
+		zd_chip_enable_hwint(&mac->chip);
+
+		spin_lock_irq(&mac->lock);
+		mac->beacon.last_update = jiffies;
+		spin_unlock_irq(&mac->lock);
+	}
+
+rearm:
+	queue_delayed_work(zd_workqueue, &mac->beacon.watchdog_work,
+			   BEACON_WATCHDOG_DELAY);
+}
+
+static void beacon_init(struct zd_mac *mac)
+{
+	INIT_DELAYED_WORK(&mac->beacon.watchdog_work, beacon_watchdog_handler);
+}
+
+static void beacon_enable(struct zd_mac *mac)
+{
+	dev_dbg_f(zd_mac_dev(mac), "\n");
+
+	mac->beacon.last_update = jiffies;
+	queue_delayed_work(zd_workqueue, &mac->beacon.watchdog_work,
+			   BEACON_WATCHDOG_DELAY);
+}
+
+static void beacon_disable(struct zd_mac *mac)
+{
+	dev_dbg_f(zd_mac_dev(mac), "\n");
+	cancel_rearming_delayed_workqueue(zd_workqueue,
+						&mac->beacon.watchdog_work);
+}
+
 #define LINK_LED_WORK_DELAY HZ
 
 static void link_led_handler(struct work_struct *work)
diff --git a/drivers/net/wireless/zd1211rw/zd_mac.h b/drivers/net/wireless/zd1211rw/zd_mac.h
index e663451..4b1edb2 100644
--- a/drivers/net/wireless/zd1211rw/zd_mac.h
+++ b/drivers/net/wireless/zd1211rw/zd_mac.h
@@ -163,6 +163,17 @@ struct housekeeping {
 	struct delayed_work link_led_work;
 };
 
+struct beacon {
+	struct delayed_work watchdog_work;
+	unsigned long last_update;
+	u16 interval;
+	u8 period;
+};
+
+enum zd_device_flags {
+	ZD_DEVICE_RUNNING,
+};
+
 #define ZD_MAC_STATS_BUFFER_SIZE 16
 
 #define ZD_MAC_MAX_ACK_WAITERS 50
@@ -174,6 +185,7 @@ struct zd_mac {
 	struct ieee80211_hw *hw;
 	struct ieee80211_vif *vif;
 	struct housekeeping housekeeping;
+	struct beacon beacon;
 	struct work_struct set_rts_cts_work;
 	struct work_struct process_intr;
 	struct zd_mc_hash multicast_hash;
@@ -182,6 +194,7 @@ struct zd_mac {
 	u8 default_regdomain;
 	int type;
 	int associated;
+	unsigned long flags;
 	struct sk_buff_head ack_wait_queue;
 	struct ieee80211_channel channels[14];
 	struct ieee80211_rate rates[12];
