From: Felix Fietkau <nbd@openwrt.org>
Date: Tue, 2 Jun 2015 10:35:46 +0200
Subject: [PATCH] ath9k: fix DMA stop sequence for AR9003+

AR93xx and newer needs to stop rx before tx to avoid getting the DMA
engine or MAC into a stuck state.
This should reduce/fix the occurence of "Failed to stop Tx DMA" logspam.

Cc: stable@vger.kernel.org
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---

--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -216,11 +216,13 @@ static bool ath_prepare_reset(struct ath
 	ath_stop_ani(sc);
 	ath9k_hw_disable_interrupts(ah);
 
-	if (!ath_drain_all_txq(sc))
-		ret = false;
-
-	if (!ath_stoprecv(sc))
-		ret = false;
+	if (AR_SREV_9300_20_OR_LATER(ah)) {
+		ret &= ath_stoprecv(sc);
+		ret &= ath_drain_all_txq(sc);
+	} else {
+		ret &= ath_drain_all_txq(sc);
+		ret &= ath_stoprecv(sc);
+	}
 
 	return ret;
 }