zd1211rw: don't let zd_mac_config_beacon() run too long from beacon interrupt handler

zd_mac_config_beacon() has only limited time to set up beacon when called from
beacon interrupt handler/worker. So do not let it retry acquiring beacon fifo
semaphore in interrupt handler. Beacon fifo semaphore should not be locked by
firmware anyway at this time, it's only locked when device is using/txing
beacon.

Signed-off-by: Jussi Kivilinna <[e-mail]>
Signed-off-by: John W. Linville <[e-mail]>

drivers/net/wireless/zd1211rw/zd_mac.c

···
 static void beacon_disable(struct zd_mac *mac);
 static void set_rts_cts(struct zd_mac *mac, unsigned int short_preamble);
 static int zd_mac_config_beacon(struct ieee80211_hw *hw,
-				struct sk_buff *beacon);
+				struct sk_buff *beacon, bool in_intr);
 
 static int zd_reg2alpha2(u8 regdomain, char *alpha2)
 {
···
 		if (mac->vif != NULL) {
 			beacon = ieee80211_beacon_get(mac->hw, mac->vif);
 			if (beacon)
-				zd_mac_config_beacon(mac->hw, beacon);
+				zd_mac_config_beacon(mac->hw, beacon, false);
 		}
 
 		zd_set_beacon_interval(&mac->chip, beacon_interval,
···
 	mutex_unlock(&mac->chip.mutex);
 }
 
-static int zd_mac_config_beacon(struct ieee80211_hw *hw, struct sk_buff *beacon)
+static int zd_mac_config_beacon(struct ieee80211_hw *hw, struct sk_buff *beacon,
+				bool in_intr)
 {
 	struct zd_mac *mac = zd_hw_mac(hw);
 	int r, ret, num_cmds, req_pos = 0;
···
 	r = zd_ioread32_locked(&mac->chip, &tmp, CR_BCN_FIFO_SEMAPHORE);
 	if (r < 0)
 		goto release_sema;
+	if (in_intr && tmp & 0x2) {
+		r = -EBUSY;
+		goto release_sema;
+	}
 
 	end_jiffies = jiffies + HZ / 2; /*~500ms*/
 	message_jiffies = jiffies + HZ / 10; /*~100ms*/
···
 	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)) {
+		if (in_intr || time_is_before_eq_jiffies(end_jiffies)) {
 			ret = -ETIMEDOUT;
 			break;
 		}
···
 	 */
 	beacon = ieee80211_beacon_get(mac->hw, mac->vif);
 	if (beacon)
-		zd_mac_config_beacon(mac->hw, beacon);
+		zd_mac_config_beacon(mac->hw, beacon, true);
 
 	spin_lock_irq(&mac->lock);
 	mac->beacon.last_update = jiffies;
···
 
 			if (beacon) {
 				zd_chip_disable_hwint(&mac->chip);
-				zd_mac_config_beacon(hw, beacon);
+				zd_mac_config_beacon(hw, beacon, false);
 				zd_chip_enable_hwint(&mac->chip);
 			}
 		}
···
 		if (beacon) {
 			zd_mac_free_cur_beacon(mac);
 
-			zd_mac_config_beacon(mac->hw, beacon);
+			zd_mac_config_beacon(mac->hw, beacon, false);
 		}
 
 		zd_set_beacon_interval(&mac->chip, interval, period, mac->type);