ath9k: use software queues for un-aggregated data packets

This is a first step for improving fairness between legacy and 802.11n
traffic, and it should also improve reliability of resets and channel
changes by keeping the hardware queue depth very short.

When an aggregation session is torn down, all packets in the retry queue
will be removed from the BAW and freed.

For all subframes that have not been transmitted yet, the A-MPDU flag
will be cleared, and a sequence number allocated. This ensures that the
next A-MPDU session will get the correct initial sequence number.
This happens both on aggregation session start and stop.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -137,6 +137,8 @@ int ath_descdma_setup(struct ath_softc *sc, struct ath_descdma *dd,
 #define ATH_AGGR_ENCRYPTDELIM      10
 /* minimum h/w qdepth to be sustained to maximize aggregation */
 #define ATH_AGGR_MIN_QDEPTH        2
+/* minimum h/w qdepth for non-aggregated traffic */
+#define ATH_NON_AGGR_MIN_QDEPTH    8
 
 #define IEEE80211_SEQ_SEQ_SHIFT    4
 #define IEEE80211_SEQ_MAX          4096
@@ -173,12 +175,6 @@ int ath_descdma_setup(struct ath_softc *sc, struct ath_descdma *dd,
 
 #define ATH_TX_COMPLETE_POLL_INT	1000
 
-enum ATH_AGGR_STATUS {
-	ATH_AGGR_DONE,
-	ATH_AGGR_BAW_CLOSED,
-	ATH_AGGR_LIMITED,
-};
-
 #define ATH_TXFIFO_DEPTH 8
 struct ath_txq {
 	int mac80211_qnum; /* mac80211 queue number, -1 means not mac80211 Q */