--- /dev/null
+--- a/drivers/net/wireless/ath/ath9k/ath9k.h
++++ b/drivers/net/wireless/ath/ath9k/ath9k.h
+@@ -298,6 +298,7 @@ struct ath_tx {
+ struct ath_descdma txdma;
+ struct ath_txq *txq_map[WME_NUM_AC];
+ u32 txq_max_pending[WME_NUM_AC];
++ u16 max_aggr_framelen[WME_NUM_AC][4][32];
+ };
+
+ struct ath_rx_edma {
+@@ -342,6 +343,7 @@ int ath_tx_init(struct ath_softc *sc, in
+ void ath_tx_cleanup(struct ath_softc *sc);
+ int ath_txq_update(struct ath_softc *sc, int qnum,
+ struct ath9k_tx_queue_info *q);
++void ath_update_max_aggr_framelen(struct ath_softc *sc, int queue, int txop);
+ int ath_tx_start(struct ieee80211_hw *hw, struct sk_buff *skb,
+ struct ath_tx_control *txctl);
+ void ath_tx_tasklet(struct ath_softc *sc);
+--- a/drivers/net/wireless/ath/ath9k/xmit.c
++++ b/drivers/net/wireless/ath/ath9k/xmit.c
+@@ -29,6 +29,8 @@
+ #define HT_LTF(_ns) (4 * (_ns))
+ #define SYMBOL_TIME(_ns) ((_ns) << 2) /* ns * 4 us */
+ #define SYMBOL_TIME_HALFGI(_ns) (((_ns) * 18 + 4) / 5) /* ns * 3.6 us */
++#define TIME_SYMBOLS(t) ((t) >> 2)
++#define TIME_SYMBOLS_HALFGI(t) (((t) * 5 - 4) / 18)
+ #define NUM_SYMBOLS_PER_USEC(_usec) (_usec >> 2)
+ #define NUM_SYMBOLS_PER_USEC_HALFGI(_usec) (((_usec*5)-4)/18)
+
+@@ -74,33 +76,6 @@ enum {
+ MCS_HT40_SGI,
+ };
+
+-static int ath_max_4ms_framelen[4][32] = {
+- [MCS_HT20] = {
+- 3212, 6432, 9648, 12864, 19300, 25736, 28952, 32172,
+- 6424, 12852, 19280, 25708, 38568, 51424, 57852, 64280,
+- 9628, 19260, 28896, 38528, 57792, 65532, 65532, 65532,
+- 12828, 25656, 38488, 51320, 65532, 65532, 65532, 65532,
+- },
+- [MCS_HT20_SGI] = {
+- 3572, 7144, 10720, 14296, 21444, 28596, 32172, 35744,
+- 7140, 14284, 21428, 28568, 42856, 57144, 64288, 65532,
+- 10700, 21408, 32112, 42816, 64228, 65532, 65532, 65532,
+- 14256, 28516, 42780, 57040, 65532, 65532, 65532, 65532,
+- },
+- [MCS_HT40] = {
+- 6680, 13360, 20044, 26724, 40092, 53456, 60140, 65532,
+- 13348, 26700, 40052, 53400, 65532, 65532, 65532, 65532,
+- 20004, 40008, 60016, 65532, 65532, 65532, 65532, 65532,
+- 26644, 53292, 65532, 65532, 65532, 65532, 65532, 65532,
+- },
+- [MCS_HT40_SGI] = {
+- 7420, 14844, 22272, 29696, 44544, 59396, 65532, 65532,
+- 14832, 29668, 44504, 59340, 65532, 65532, 65532, 65532,
+- 22232, 44464, 65532, 65532, 65532, 65532, 65532, 65532,
+- 29616, 59232, 65532, 65532, 65532, 65532, 65532, 65532,
+- }
+-};
+-
+ /*********************/
+ /* Aggregation logic */
+ /*********************/
+@@ -648,6 +623,7 @@ static u32 ath_lookup_rate(struct ath_so
+ struct ieee80211_tx_rate *rates;
+ u32 max_4ms_framelen, frmlen;
+ u16 aggr_limit, bt_aggr_limit, legacy = 0;
++ int q = tid->ac->txq->mac80211_qnum;
+ int i;
+
+ skb = bf->bf_mpdu;
+@@ -680,7 +656,7 @@ static u32 ath_lookup_rate(struct ath_so
+ if (rates[i].flags & IEEE80211_TX_RC_SHORT_GI)
+ modeidx++;
+
+- frmlen = ath_max_4ms_framelen[modeidx][rates[i].idx];
++ frmlen = sc->tx.max_aggr_framelen[q][modeidx][rates[i].idx];
+ max_4ms_framelen = min(max_4ms_framelen, frmlen);
+ }
+
+@@ -927,6 +903,44 @@ static u32 ath_pkt_duration(struct ath_s
+ return duration;
+ }
+
++static int ath_max_framelen(int usec, int mcs, bool ht40, bool sgi)
++{
++ int streams = HT_RC_2_STREAMS(mcs);
++ int symbols, bits;
++ int bytes = 0;
++
++ symbols = sgi ? TIME_SYMBOLS_HALFGI(usec) : TIME_SYMBOLS(usec);
++ bits = symbols * bits_per_symbol[mcs % 8][ht40] * streams;
++ bits -= OFDM_PLCP_BITS;
++ bytes = bits / 8;
++ bytes -= L_STF + L_LTF + L_SIG + HT_SIG + HT_STF + HT_LTF(streams);
++ if (bytes > 65532)
++ bytes = 65532;
++
++ return bytes;
++}
++
++void ath_update_max_aggr_framelen(struct ath_softc *sc, int queue, int txop)
++{
++ u16 *cur_ht20, *cur_ht20_sgi, *cur_ht40, *cur_ht40_sgi;
++ int mcs;
++
++ /* 4ms is the default (and maximum) duration */
++ if (!txop || txop > 4096)
++ txop = 4096;
++
++ cur_ht20 = sc->tx.max_aggr_framelen[queue][MCS_HT20];
++ cur_ht20_sgi = sc->tx.max_aggr_framelen[queue][MCS_HT20_SGI];
++ cur_ht40 = sc->tx.max_aggr_framelen[queue][MCS_HT40];
++ cur_ht40_sgi = sc->tx.max_aggr_framelen[queue][MCS_HT40_SGI];
++ for (mcs = 0; mcs < 32; mcs++) {
++ cur_ht20[mcs] = ath_max_framelen(txop, mcs, false, false);
++ cur_ht20_sgi[mcs] = ath_max_framelen(txop, mcs, false, true);
++ cur_ht40[mcs] = ath_max_framelen(txop, mcs, true, false);
++ cur_ht40_sgi[mcs] = ath_max_framelen(txop, mcs, true, true);
++ }
++}
++
+ static void ath_buf_set_rate(struct ath_softc *sc, struct ath_buf *bf,
+ struct ath_tx_info *info, int len)
+ {