diff --git a/[refs] b/[refs]
index 246a0df5832f..dd8aaea93e4d 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f241b244dd4703a560c74e2538f27fd466c8d41f
+refs/heads/master: 1981e881fd32160bf886a09b12794c640aafffb3
diff --git a/trunk/drivers/net/wireless/ath/carl9170/tx.c b/trunk/drivers/net/wireless/ath/carl9170/tx.c
index 84377cf580e0..ef4ec0da6e49 100644
--- a/trunk/drivers/net/wireless/ath/carl9170/tx.c
+++ b/trunk/drivers/net/wireless/ath/carl9170/tx.c
@@ -1485,6 +1485,13 @@ void carl9170_op_tx(struct ieee80211_hw *hw,
 	}
 
 	if (info->flags & IEEE80211_TX_CTL_AMPDU) {
+		/* to static code analyzers and reviewers:
+		 * mac80211 guarantees that a valid "sta"
+		 * reference is present, if a frame is to
+		 * be part of an ampdu. Hence any extra
+		 * sta == NULL checks are redundant in this
+		 * special case.
+		 */
 		run = carl9170_tx_ampdu_queue(ar, sta, skb);
 		if (run)
 			carl9170_tx_ampdu(ar);