ath9k: Implement an algorithm for Antenna diversity and combining

This algorithm chooses the best main and alt lna out of
LNA1, LNA2, LNA1+LNA2 and LNA1-LNA2 to improve rx for single
chain chips(AR9285). This would greatly improve rx when there
is only one antenna is connected with AR9285.

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index f0197a6046aba3dad7d299b0f1989b528bc7ceeb..5fe570bb5c4c2d01d32f4d72d0296dd5c7d077b4 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -481,6 +481,60 @@ struct ath_led {
 void ath_init_leds(struct ath_softc *sc);
 void ath_deinit_leds(struct ath_softc *sc);
 
+/* Antenna diversity/combining */
+#define ATH_ANT_RX_CURRENT_SHIFT 4
+#define ATH_ANT_RX_MAIN_SHIFT 2
+#define ATH_ANT_RX_MASK 0x3
+
+#define ATH_ANT_DIV_COMB_SHORT_SCAN_INTR 50
+#define ATH_ANT_DIV_COMB_SHORT_SCAN_PKTCOUNT 0x100
+#define ATH_ANT_DIV_COMB_MAX_PKTCOUNT 0x200
+#define ATH_ANT_DIV_COMB_INIT_COUNT 95
+#define ATH_ANT_DIV_COMB_MAX_COUNT 100
+#define ATH_ANT_DIV_COMB_ALT_ANT_RATIO 30
+#define ATH_ANT_DIV_COMB_ALT_ANT_RATIO2 20
+
+#define ATH_ANT_DIV_COMB_LNA1_LNA2_DELTA -3
+#define ATH_ANT_DIV_COMB_LNA1_LNA2_SWITCH_DELTA -1
+#define ATH_ANT_DIV_COMB_LNA1_DELTA_HI -4
+#define ATH_ANT_DIV_COMB_LNA1_DELTA_MID -2
+#define ATH_ANT_DIV_COMB_LNA1_DELTA_LOW 2
+
+enum ath9k_ant_div_comb_lna_conf {
+       ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2,
+       ATH_ANT_DIV_COMB_LNA2,
+       ATH_ANT_DIV_COMB_LNA1,
+       ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2,
+};
+
+struct ath_ant_comb {
+       u16 count;
+       u16 total_pkt_count;
+       bool scan;
+       bool scan_not_start;
+       int main_total_rssi;
+       int alt_total_rssi;
+       int alt_recv_cnt;
+       int main_recv_cnt;
+       int rssi_lna1;
+       int rssi_lna2;
+       int rssi_add;
+       int rssi_sub;
+       int rssi_first;
+       int rssi_second;
+       int rssi_third;
+       bool alt_good;
+       int quick_scan_cnt;
+       int main_conf;
+       enum ath9k_ant_div_comb_lna_conf first_quick_scan_conf;
+       enum ath9k_ant_div_comb_lna_conf second_quick_scan_conf;
+       int first_bias;
+       int second_bias;
+       bool first_ratio;
+       bool second_ratio;
+       unsigned long scan_start_time;
+};
+
 /********************/
 /* Main driver core */
 /********************/
@@ -597,6 +651,8 @@ struct ath_softc {
        struct ath_btcoex btcoex;
 
        struct ath_descdma txsdma;
+
+       struct ath_ant_comb ant_comb;
 };
 
 struct ath_wiphy {

diff --git a/drivers/net/wireless/ath/ath9k/init.c b/drivers/net/wireless/ath/ath9k/init.c
index 3dbff8d077667a224660464eddfcc2c1e008ea61..e7c07b3370ccee4a69ded42de4ad87204a49cfa4 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/init.c
+++ b/drivers/net/wireless/ath/ath9k/init.c
@@ -531,6 +531,9 @@ static void ath9k_init_misc(struct ath_softc *sc)
                sc->beacon.bslot[i] = NULL;
                sc->beacon.bslot_aphy[i] = NULL;
        }
+
+       if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_ANT_DIV_COMB)
+               sc->ant_comb.count = ATH_ANT_DIV_COMB_INIT_COUNT;
 }
 
 static int ath9k_init_softc(u16 devid, struct ath_softc *sc, u16 subsysid,

diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 534a91bcc1d980a28d26ae3ebdef57e2c99566ca..b32c8f033d20ecc41933f28f019ec9271eedb86c 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -19,6 +19,15 @@
 
 #define SKB_CB_ATHBUF(__skb)   (*((struct ath_buf **)__skb->cb))
 
+static inline bool ath_is_alt_ant_ratio_better(int alt_ratio, int maxdelta,
+                                              int mindelta, int main_rssi_avg,
+                                              int alt_rssi_avg, int pkt_count)
+{
+       return (((alt_ratio >= ATH_ANT_DIV_COMB_ALT_ANT_RATIO2) &&
+               (alt_rssi_avg > main_rssi_avg + maxdelta)) ||
+               (alt_rssi_avg > main_rssi_avg + mindelta)) && (pkt_count > 50);
+}
+
 static inline bool ath9k_check_auto_sleep(struct ath_softc *sc)
 {
        return sc->ps_enabled &&
@@ -1076,6 +1085,539 @@ static void ath9k_rx_skb_postprocess(struct ath_common *common,
                rxs->flag &= ~RX_FLAG_DECRYPTED;
 }
 
+static void ath_lnaconf_alt_good_scan(struct ath_ant_comb *antcomb,
+                                     struct ath_hw_antcomb_conf ant_conf,
+                                     int main_rssi_avg)
+{
+       antcomb->quick_scan_cnt = 0;
+
+       if (ant_conf.main_lna_conf == ATH_ANT_DIV_COMB_LNA2)
+               antcomb->rssi_lna2 = main_rssi_avg;
+       else if (ant_conf.main_lna_conf == ATH_ANT_DIV_COMB_LNA1)
+               antcomb->rssi_lna1 = main_rssi_avg;
+
+       switch ((ant_conf.main_lna_conf << 4) | ant_conf.alt_lna_conf) {
+       case (0x10): /* LNA2 A-B */
+               antcomb->main_conf = ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
+               antcomb->first_quick_scan_conf =
+                       ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
+               antcomb->second_quick_scan_conf = ATH_ANT_DIV_COMB_LNA1;
+               break;
+       case (0x20): /* LNA1 A-B */
+               antcomb->main_conf = ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
+               antcomb->first_quick_scan_conf =
+                       ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
+               antcomb->second_quick_scan_conf = ATH_ANT_DIV_COMB_LNA2;
+               break;
+       case (0x21): /* LNA1 LNA2 */
+               antcomb->main_conf = ATH_ANT_DIV_COMB_LNA2;
+               antcomb->first_quick_scan_conf =
+                       ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
+               antcomb->second_quick_scan_conf =
+                       ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
+               break;
+       case (0x12): /* LNA2 LNA1 */
+               antcomb->main_conf = ATH_ANT_DIV_COMB_LNA1;
+               antcomb->first_quick_scan_conf =
+                       ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
+               antcomb->second_quick_scan_conf =
+                       ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
+               break;
+       case (0x13): /* LNA2 A+B */
+               antcomb->main_conf = ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
+               antcomb->first_quick_scan_conf =
+                       ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
+               antcomb->second_quick_scan_conf = ATH_ANT_DIV_COMB_LNA1;
+               break;
+       case (0x23): /* LNA1 A+B */
+               antcomb->main_conf = ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
+               antcomb->first_quick_scan_conf =
+                       ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
+               antcomb->second_quick_scan_conf = ATH_ANT_DIV_COMB_LNA2;
+               break;
+       default:
+               break;
+       }
+}
+
+static void ath_select_ant_div_from_quick_scan(struct ath_ant_comb *antcomb,
+                               struct ath_hw_antcomb_conf *div_ant_conf,
+                               int main_rssi_avg, int alt_rssi_avg,
+                               int alt_ratio)
+{
+       /* alt_good */
+       switch (antcomb->quick_scan_cnt) {
+       case 0:
+               /* set alt to main, and alt to first conf */
+               div_ant_conf->main_lna_conf = antcomb->main_conf;
+               div_ant_conf->alt_lna_conf = antcomb->first_quick_scan_conf;
+               break;
+       case 1:
+               /* set alt to main, and alt to first conf */
+               div_ant_conf->main_lna_conf = antcomb->main_conf;
+               div_ant_conf->alt_lna_conf = antcomb->second_quick_scan_conf;
+               antcomb->rssi_first = main_rssi_avg;
+               antcomb->rssi_second = alt_rssi_avg;
+
+               if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA1) {
+                       /* main is LNA1 */
+                       if (ath_is_alt_ant_ratio_better(alt_ratio,
+                                               ATH_ANT_DIV_COMB_LNA1_DELTA_HI,
+                                               ATH_ANT_DIV_COMB_LNA1_DELTA_LOW,
+                                               main_rssi_avg, alt_rssi_avg,
+                                               antcomb->total_pkt_count))
+                               antcomb->first_ratio = true;
+                       else
+                               antcomb->first_ratio = false;
+               } else if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA2) {
+                       if (ath_is_alt_ant_ratio_better(alt_ratio,
+                                               ATH_ANT_DIV_COMB_LNA1_DELTA_MID,
+                                               ATH_ANT_DIV_COMB_LNA1_DELTA_LOW,
+                                               main_rssi_avg, alt_rssi_avg,
+                                               antcomb->total_pkt_count))
+                               antcomb->first_ratio = true;
+                       else
+                               antcomb->first_ratio = false;
+               } else {
+                       if ((((alt_ratio >= ATH_ANT_DIV_COMB_ALT_ANT_RATIO2) &&
+                           (alt_rssi_avg > main_rssi_avg +
+                           ATH_ANT_DIV_COMB_LNA1_DELTA_HI)) ||
+                           (alt_rssi_avg > main_rssi_avg)) &&
+                           (antcomb->total_pkt_count > 50))
+                               antcomb->first_ratio = true;
+                       else
+                               antcomb->first_ratio = false;
+               }
+               break;
+       case 2:
+               antcomb->alt_good = false;
+               antcomb->scan_not_start = false;
+               antcomb->scan = false;
+               antcomb->rssi_first = main_rssi_avg;
+               antcomb->rssi_third = alt_rssi_avg;
+
+               if (antcomb->second_quick_scan_conf == ATH_ANT_DIV_COMB_LNA1)
+                       antcomb->rssi_lna1 = alt_rssi_avg;
+               else if (antcomb->second_quick_scan_conf ==
+                        ATH_ANT_DIV_COMB_LNA2)
+                       antcomb->rssi_lna2 = alt_rssi_avg;
+               else if (antcomb->second_quick_scan_conf ==
+                        ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2) {
+                       if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA2)
+                               antcomb->rssi_lna2 = main_rssi_avg;
+                       else if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA1)
+                               antcomb->rssi_lna1 = main_rssi_avg;
+               }
+
+               if (antcomb->rssi_lna2 > antcomb->rssi_lna1 +
+                   ATH_ANT_DIV_COMB_LNA1_LNA2_SWITCH_DELTA)
+                       div_ant_conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA2;
+               else
+                       div_ant_conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA1;
+
+               if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA1) {
+                       if (ath_is_alt_ant_ratio_better(alt_ratio,
+                                               ATH_ANT_DIV_COMB_LNA1_DELTA_HI,
+                                               ATH_ANT_DIV_COMB_LNA1_DELTA_LOW,
+                                               main_rssi_avg, alt_rssi_avg,
+                                               antcomb->total_pkt_count))
+                               antcomb->second_ratio = true;
+                       else
+                               antcomb->second_ratio = false;
+               } else if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA2) {
+                       if (ath_is_alt_ant_ratio_better(alt_ratio,
+                                               ATH_ANT_DIV_COMB_LNA1_DELTA_MID,
+                                               ATH_ANT_DIV_COMB_LNA1_DELTA_LOW,
+                                               main_rssi_avg, alt_rssi_avg,
+                                               antcomb->total_pkt_count))
+                               antcomb->second_ratio = true;
+                       else
+                               antcomb->second_ratio = false;
+               } else {
+                       if ((((alt_ratio >= ATH_ANT_DIV_COMB_ALT_ANT_RATIO2) &&
+                           (alt_rssi_avg > main_rssi_avg +
+                           ATH_ANT_DIV_COMB_LNA1_DELTA_HI)) ||
+                           (alt_rssi_avg > main_rssi_avg)) &&
+                           (antcomb->total_pkt_count > 50))
+                               antcomb->second_ratio = true;
+                       else
+                               antcomb->second_ratio = false;
+               }
+
+               /* set alt to the conf with maximun ratio */
+               if (antcomb->first_ratio && antcomb->second_ratio) {
+                       if (antcomb->rssi_second > antcomb->rssi_third) {
+                               /* first alt*/
+                               if ((antcomb->first_quick_scan_conf ==
+                                   ATH_ANT_DIV_COMB_LNA1) ||
+                                   (antcomb->first_quick_scan_conf ==
+                                   ATH_ANT_DIV_COMB_LNA2))
+                                       /* Set alt LNA1 or LNA2*/
+                                       if (div_ant_conf->main_lna_conf ==
+                                           ATH_ANT_DIV_COMB_LNA2)
+                                               div_ant_conf->alt_lna_conf =
+                                                       ATH_ANT_DIV_COMB_LNA1;
+                                       else
+                                               div_ant_conf->alt_lna_conf =
+                                                       ATH_ANT_DIV_COMB_LNA2;
+                               else
+                                       /* Set alt to A+B or A-B */
+                                       div_ant_conf->alt_lna_conf =
+                                               antcomb->first_quick_scan_conf;
+                       } else if ((antcomb->second_quick_scan_conf ==
+                                  ATH_ANT_DIV_COMB_LNA1) ||
+                                  (antcomb->second_quick_scan_conf ==
+                                  ATH_ANT_DIV_COMB_LNA2)) {
+                               /* Set alt LNA1 or LNA2 */
+                               if (div_ant_conf->main_lna_conf ==
+                                   ATH_ANT_DIV_COMB_LNA2)
+                                       div_ant_conf->alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                               else
+                                       div_ant_conf->alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA2;
+                       } else {
+                               /* Set alt to A+B or A-B */
+                               div_ant_conf->alt_lna_conf =
+                                       antcomb->second_quick_scan_conf;
+                       }
+               } else if (antcomb->first_ratio) {
+                       /* first alt */
+                       if ((antcomb->first_quick_scan_conf ==
+                           ATH_ANT_DIV_COMB_LNA1) ||
+                           (antcomb->first_quick_scan_conf ==
+                           ATH_ANT_DIV_COMB_LNA2))
+                                       /* Set alt LNA1 or LNA2 */
+                               if (div_ant_conf->main_lna_conf ==
+                                   ATH_ANT_DIV_COMB_LNA2)
+                                       div_ant_conf->alt_lna_conf =
+                                                       ATH_ANT_DIV_COMB_LNA1;
+                               else
+                                       div_ant_conf->alt_lna_conf =
+                                                       ATH_ANT_DIV_COMB_LNA2;
+                       else
+                               /* Set alt to A+B or A-B */
+                               div_ant_conf->alt_lna_conf =
+                                               antcomb->first_quick_scan_conf;
+               } else if (antcomb->second_ratio) {
+                               /* second alt */
+                       if ((antcomb->second_quick_scan_conf ==
+                           ATH_ANT_DIV_COMB_LNA1) ||
+                           (antcomb->second_quick_scan_conf ==
+                           ATH_ANT_DIV_COMB_LNA2))
+                               /* Set alt LNA1 or LNA2 */
+                               if (div_ant_conf->main_lna_conf ==
+                                   ATH_ANT_DIV_COMB_LNA2)
+                                       div_ant_conf->alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                               else
+                                       div_ant_conf->alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA2;
+                       else
+                               /* Set alt to A+B or A-B */
+                               div_ant_conf->alt_lna_conf =
+                                               antcomb->second_quick_scan_conf;
+               } else {
+                       /* main is largest */
+                       if ((antcomb->main_conf == ATH_ANT_DIV_COMB_LNA1) ||
+                           (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA2))
+                               /* Set alt LNA1 or LNA2 */
+                               if (div_ant_conf->main_lna_conf ==
+                                   ATH_ANT_DIV_COMB_LNA2)
+                                       div_ant_conf->alt_lna_conf =
+                                                       ATH_ANT_DIV_COMB_LNA1;
+                               else
+                                       div_ant_conf->alt_lna_conf =
+                                                       ATH_ANT_DIV_COMB_LNA2;
+                       else
+                               /* Set alt to A+B or A-B */
+                               div_ant_conf->alt_lna_conf = antcomb->main_conf;
+               }
+               break;
+       default:
+               break;
+       }
+}
+
+void ath_ant_div_conf_fast_divbias(struct ath_hw_antcomb_conf *ant_conf)
+{
+       /* Adjust the fast_div_bias based on main and alt lna conf */
+       switch ((ant_conf->main_lna_conf << 4) | ant_conf->alt_lna_conf) {
+       case (0x01): /* A-B LNA2 */
+               ant_conf->fast_div_bias = 0x3b;
+               break;
+       case (0x02): /* A-B LNA1 */
+               ant_conf->fast_div_bias = 0x3d;
+               break;
+       case (0x03): /* A-B A+B */
+               ant_conf->fast_div_bias = 0x1;
+               break;
+       case (0x10): /* LNA2 A-B */
+               ant_conf->fast_div_bias = 0x7;
+               break;
+       case (0x12): /* LNA2 LNA1 */
+               ant_conf->fast_div_bias = 0x2;
+               break;
+       case (0x13): /* LNA2 A+B */
+               ant_conf->fast_div_bias = 0x7;
+               break;
+       case (0x20): /* LNA1 A-B */
+               ant_conf->fast_div_bias = 0x6;
+               break;
+       case (0x21): /* LNA1 LNA2 */
+               ant_conf->fast_div_bias = 0x0;
+               break;
+       case (0x23): /* LNA1 A+B */
+               ant_conf->fast_div_bias = 0x6;
+               break;
+       case (0x30): /* A+B A-B */
+               ant_conf->fast_div_bias = 0x1;
+               break;
+       case (0x31): /* A+B LNA2 */
+               ant_conf->fast_div_bias = 0x3b;
+               break;
+       case (0x32): /* A+B LNA1 */
+               ant_conf->fast_div_bias = 0x3d;
+               break;
+       default:
+               break;
+       }
+}
+
+/* Antenna diversity and combining */
+static void ath_ant_comb_scan(struct ath_softc *sc, struct ath_rx_status *rs)
+{
+       struct ath_hw_antcomb_conf div_ant_conf;
+       struct ath_ant_comb *antcomb = &sc->ant_comb;
+       int alt_ratio = 0, alt_rssi_avg = 0, main_rssi_avg = 0, curr_alt_set;
+       int curr_main_set, curr_bias;
+       int main_rssi = rs->rs_rssi_ctl0;
+       int alt_rssi = rs->rs_rssi_ctl1;
+       int rx_ant_conf,  main_ant_conf;
+       bool short_scan = false;
+
+       rx_ant_conf = (rs->rs_rssi_ctl2 >> ATH_ANT_RX_CURRENT_SHIFT) &
+                      ATH_ANT_RX_MASK;
+       main_ant_conf = (rs->rs_rssi_ctl2 >> ATH_ANT_RX_MAIN_SHIFT) &
+                        ATH_ANT_RX_MASK;
+
+       /* Record packet only when alt_rssi is positive */
+       if (alt_rssi > 0) {
+               antcomb->total_pkt_count++;
+               antcomb->main_total_rssi += main_rssi;
+               antcomb->alt_total_rssi  += alt_rssi;
+               if (main_ant_conf == rx_ant_conf)
+                       antcomb->main_recv_cnt++;
+               else
+                       antcomb->alt_recv_cnt++;
+       }
+
+       /* Short scan check */
+       if (antcomb->scan && antcomb->alt_good) {
+               if (time_after(jiffies, antcomb->scan_start_time +
+                   msecs_to_jiffies(ATH_ANT_DIV_COMB_SHORT_SCAN_INTR)))
+                       short_scan = true;
+               else
+                       if (antcomb->total_pkt_count ==
+                           ATH_ANT_DIV_COMB_SHORT_SCAN_PKTCOUNT) {
+                               alt_ratio = ((antcomb->alt_recv_cnt * 100) /
+                                           antcomb->total_pkt_count);
+                               if (alt_ratio < ATH_ANT_DIV_COMB_ALT_ANT_RATIO)
+                                       short_scan = true;
+                       }
+       }
+
+       if (((antcomb->total_pkt_count < ATH_ANT_DIV_COMB_MAX_PKTCOUNT) ||
+           rs->rs_moreaggr) && !short_scan)
+               return;
+
+       if (antcomb->total_pkt_count) {
+               alt_ratio = ((antcomb->alt_recv_cnt * 100) /
+                            antcomb->total_pkt_count);
+               main_rssi_avg = (antcomb->main_total_rssi /
+                                antcomb->total_pkt_count);
+               alt_rssi_avg = (antcomb->alt_total_rssi /
+                                antcomb->total_pkt_count);
+       }
+
+
+       ath9k_hw_antdiv_comb_conf_get(sc->sc_ah, &div_ant_conf);
+       curr_alt_set = div_ant_conf.alt_lna_conf;
+       curr_main_set = div_ant_conf.main_lna_conf;
+       curr_bias = div_ant_conf.fast_div_bias;
+
+       antcomb->count++;
+
+       if (antcomb->count == ATH_ANT_DIV_COMB_MAX_COUNT) {
+               if (alt_ratio > ATH_ANT_DIV_COMB_ALT_ANT_RATIO) {
+                       ath_lnaconf_alt_good_scan(antcomb, div_ant_conf,
+                                                 main_rssi_avg);
+                       antcomb->alt_good = true;
+               } else {
+                       antcomb->alt_good = false;
+               }
+
+               antcomb->count = 0;
+               antcomb->scan = true;
+               antcomb->scan_not_start = true;
+       }
+
+       if (!antcomb->scan) {
+               if (alt_ratio > ATH_ANT_DIV_COMB_ALT_ANT_RATIO) {
+                       if (curr_alt_set == ATH_ANT_DIV_COMB_LNA2) {
+                               /* Switch main and alt LNA */
+                               div_ant_conf.main_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA2;
+                               div_ant_conf.alt_lna_conf  =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                       } else if (curr_alt_set == ATH_ANT_DIV_COMB_LNA1) {
+                               div_ant_conf.main_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                               div_ant_conf.alt_lna_conf  =
+                                               ATH_ANT_DIV_COMB_LNA2;
+                       }
+
+                       goto div_comb_done;
+               } else if ((curr_alt_set != ATH_ANT_DIV_COMB_LNA1) &&
+                          (curr_alt_set != ATH_ANT_DIV_COMB_LNA2)) {
+                       /* Set alt to another LNA */
+                       if (curr_main_set == ATH_ANT_DIV_COMB_LNA2)
+                               div_ant_conf.alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                       else if (curr_main_set == ATH_ANT_DIV_COMB_LNA1)
+                               div_ant_conf.alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA2;
+
+                       goto div_comb_done;
+               }
+
+               if ((alt_rssi_avg < (main_rssi_avg +
+                   ATH_ANT_DIV_COMB_LNA1_LNA2_DELTA)))
+                       goto div_comb_done;
+       }
+
+       if (!antcomb->scan_not_start) {
+               switch (curr_alt_set) {
+               case ATH_ANT_DIV_COMB_LNA2:
+                       antcomb->rssi_lna2 = alt_rssi_avg;
+                       antcomb->rssi_lna1 = main_rssi_avg;
+                       antcomb->scan = true;
+                       /* set to A+B */
+                       div_ant_conf.main_lna_conf =
+                               ATH_ANT_DIV_COMB_LNA1;
+                       div_ant_conf.alt_lna_conf  =
+                               ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
+                       break;
+               case ATH_ANT_DIV_COMB_LNA1:
+                       antcomb->rssi_lna1 = alt_rssi_avg;
+                       antcomb->rssi_lna2 = main_rssi_avg;
+                       antcomb->scan = true;
+                       /* set to A+B */
+                       div_ant_conf.main_lna_conf = ATH_ANT_DIV_COMB_LNA2;
+                       div_ant_conf.alt_lna_conf  =
+                               ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
+                       break;
+               case ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2:
+                       antcomb->rssi_add = alt_rssi_avg;
+                       antcomb->scan = true;
+                       /* set to A-B */
+                       div_ant_conf.alt_lna_conf =
+                               ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
+                       break;
+               case ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2:
+                       antcomb->rssi_sub = alt_rssi_avg;
+                       antcomb->scan = false;
+                       if (antcomb->rssi_lna2 >
+                           (antcomb->rssi_lna1 +
+                           ATH_ANT_DIV_COMB_LNA1_LNA2_SWITCH_DELTA)) {
+                               /* use LNA2 as main LNA */
+                               if ((antcomb->rssi_add > antcomb->rssi_lna1) &&
+                                   (antcomb->rssi_add > antcomb->rssi_sub)) {
+                                       /* set to A+B */
+                                       div_ant_conf.main_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA2;
+                                       div_ant_conf.alt_lna_conf  =
+                                               ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
+                               } else if (antcomb->rssi_sub >
+                                          antcomb->rssi_lna1) {
+                                       /* set to A-B */
+                                       div_ant_conf.main_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA2;
+                                       div_ant_conf.alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
+                               } else {
+                                       /* set to LNA1 */
+                                       div_ant_conf.main_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA2;
+                                       div_ant_conf.alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                               }
+                       } else {
+                               /* use LNA1 as main LNA */
+                               if ((antcomb->rssi_add > antcomb->rssi_lna2) &&
+                                   (antcomb->rssi_add > antcomb->rssi_sub)) {
+                                       /* set to A+B */
+                                       div_ant_conf.main_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                                       div_ant_conf.alt_lna_conf  =
+                                               ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
+                               } else if (antcomb->rssi_sub >
+                                          antcomb->rssi_lna1) {
+                                       /* set to A-B */
+                                       div_ant_conf.main_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                                       div_ant_conf.alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
+                               } else {
+                                       /* set to LNA2 */
+                                       div_ant_conf.main_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                                       div_ant_conf.alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA2;
+                               }
+                       }
+                       break;
+               default:
+                       break;
+               }
+       } else {
+               if (!antcomb->alt_good) {
+                       antcomb->scan_not_start = false;
+                       /* Set alt to another LNA */
+                       if (curr_main_set == ATH_ANT_DIV_COMB_LNA2) {
+                               div_ant_conf.main_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA2;
+                               div_ant_conf.alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                       } else if (curr_main_set == ATH_ANT_DIV_COMB_LNA1) {
+                               div_ant_conf.main_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA1;
+                               div_ant_conf.alt_lna_conf =
+                                               ATH_ANT_DIV_COMB_LNA2;
+                       }
+                       goto div_comb_done;
+               }
+       }
+
+       ath_select_ant_div_from_quick_scan(antcomb, &div_ant_conf,
+                                          main_rssi_avg, alt_rssi_avg,
+                                          alt_ratio);
+
+       antcomb->quick_scan_cnt++;
+
+div_comb_done:
+       ath_ant_div_conf_fast_divbias(&div_ant_conf);
+
+       ath9k_hw_antdiv_comb_conf_set(sc->sc_ah, &div_ant_conf);
+
+       antcomb->scan_start_time = jiffies;
+       antcomb->total_pkt_count = 0;
+       antcomb->main_total_rssi = 0;
+       antcomb->alt_total_rssi = 0;
+       antcomb->main_recv_cnt = 0;
+       antcomb->alt_recv_cnt = 0;
+}
+
 int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp)
 {
        struct ath_buf *bf;
@@ -1213,6 +1755,9 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp)
                                              PS_WAIT_FOR_PSPOLL_DATA))))
                        ath_rx_ps(sc, skb);
 
+               if (ah->caps.hw_caps & ATH9K_HW_CAP_ANT_DIV_COMB)
+                       ath_ant_comb_scan(sc, &rs);
+
                ath_rx_send_to_mac80211(hw, sc, skb, rxs);
 
 requeue: