zd1211rw: reset device when CR_BCN_FIFO_SEMAPHORE freezes in beacon setup

When driver fails to acquire device semaphore lock, device usually
freezes soon afterwards. So failing to acquire lock indicates us that
not everything is going right in device/fw. So reset device when
this happens.
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/zd1211rw/zd_mac.c

@@ -703,7 +703,7 @@ static int zd_mac_config_beacon(struct ieee80211_hw *hw, struct sk_buff *beacon)
 				dev_err(zd_mac_dev(mac),
 						"Giving up beacon config.\n");
 				r = -ETIMEDOUT;
-				goto release_sema;
+				goto reset_device;
 			}
 		}
 		msleep(20);
@@ -770,6 +770,17 @@ static int zd_mac_config_beacon(struct ieee80211_hw *hw, struct sk_buff *beacon)
 	mutex_unlock(&mac->chip.mutex);
 	kfree(ioreqs);
 	return r;
+
+reset_device:
+	mutex_unlock(&mac->chip.mutex);
+	kfree(ioreqs);
+
+	/* semaphore stuck, reset device to avoid fw freeze later */
+	dev_warn(zd_mac_dev(mac), "CR_BCN_FIFO_SEMAPHORE stuck, "
+				  "reseting device...");
+	usb_queue_reset_device(mac->chip.usb.intf);
+
+	return r;
 }
 
 static int fill_ctrlset(struct zd_mac *mac,