wl12xx: don't queue a new dummy packet if one is already pending

The firmware only asks for one dummy packet at a time, but sometimes we
are unable to provide it before a FW timer expires. When this happens,
the FW will re-request the dummy packet. If a packet is still queued in
the driver queues, do nothing in this case.

This prevents spurious dummy packets from clogging up the VO AC.
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>

drivers/net/wireless/wl12xx/main.c

@@ -1540,7 +1540,13 @@ static void wl1271_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
 int wl1271_tx_dummy_packet(struct wl1271 *wl)
 {
 	unsigned long flags;
-	int q = wl1271_tx_get_queue(skb_get_queue_mapping(wl->dummy_packet));
+	int q;
+
+	/* no need to queue a new dummy packet if one is already pending */
+	if (test_bit(WL1271_FLAG_DUMMY_PACKET_PENDING, &wl->flags))
+		return 0;
+
+	q = wl1271_tx_get_queue(skb_get_queue_mapping(wl->dummy_packet));
 
 	spin_lock_irqsave(&wl->wl_lock, flags);
 	set_bit(WL1271_FLAG_DUMMY_PACKET_PENDING, &wl->flags);