diff --git a/[refs] b/[refs]
index 48827b064864..00727cf62ba7 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 77c2061d10a408d0220c2b0e7faefe52d9c41008
+refs/heads/master: de0f648dc769daabd0842a8dcf439d5f1f23e07f
diff --git a/trunk/drivers/net/wireless/ath/ath9k/xmit.c b/trunk/drivers/net/wireless/ath/ath9k/xmit.c
index 859aa4ab0769..f63f6a944d62 100644
--- a/trunk/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/trunk/drivers/net/wireless/ath/ath9k/xmit.c
@@ -2279,6 +2279,17 @@ void ath_tx_edma_tasklet(struct ath_softc *sc)
 
 		txok = !(txs.ts_status & ATH9K_TXERR_MASK);
 
+		/*
+		 * Make sure null func frame is acked before configuring
+		 * hw into ps mode.
+		 */
+		if (bf->bf_isnullfunc && txok) {
+			if ((sc->ps_flags & PS_ENABLED))
+				ath9k_enable_ps(sc);
+			else
+				sc->ps_flags |= PS_NULLFUNC_COMPLETED;
+		}
+
 		if (!bf_isampdu(bf)) {
 			bf->bf_retries = txs.ts_longretry;
 			if (txs.ts_status & ATH9K_TXERR_XRETRY)