rt2x00: Don't enable broad- and multicast buffering on USB devices

Since rt2x00 USB devices have no chance to know when a beacon was sent
out in AP mode currently all broad- and multicast traffic is buffered in
mac80211 but never sent out at all.

Unfortunately we have no chance in sending the traffic out after a
DTIM beacon due to hw limitations. Hence, instead of never sending the
buffered traffic out better send it out immediately.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Reported-by: Lauri Hintsala <lauri.hintsala@bluegiga.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2800lib.c b/drivers/net/wireless/rt2x00/rt2800lib.c
index 76b8783..99b505f 100644
--- a/drivers/net/wireless/rt2x00/rt2800lib.c
+++ b/drivers/net/wireless/rt2x00/rt2800lib.c
@@ -3164,11 +3164,20 @@
 	 * Initialize all hw fields.
 	 */
 	rt2x00dev->hw->flags =
-	    IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING |
 	    IEEE80211_HW_SIGNAL_DBM |
 	    IEEE80211_HW_SUPPORTS_PS |
 	    IEEE80211_HW_PS_NULLFUNC_STACK |
 	    IEEE80211_HW_AMPDU_AGGREGATION;
+	/*
+	 * Don't set IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING for USB devices
+	 * unless we are capable of sending the buffered frames out after the
+	 * DTIM transmission using rt2x00lib_beacondone. This will send out
+	 * multicast and broadcast traffic immediately instead of buffering it
+	 * infinitly and thus dropping it after some time.
+	 */
+	if (!rt2x00_is_usb(rt2x00dev))
+		rt2x00dev->hw->flags |=
+			IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING;
 
 	SET_IEEE80211_DEV(rt2x00dev->hw, rt2x00dev->dev);
 	SET_IEEE80211_PERM_ADDR(rt2x00dev->hw,