ath9k: stomp audio profiles on weak signal strength

On lower WLAN signal strength, WLAN downlink traffic might suffer
from retransmissions. At the mean time, playing SCO/A2DP profiles
is affecting WLAN stability. In such scenario, by stomping SCO/A2DP
BT traffic completely for a BTCOEX period, gives WLAN traffic an
oppertunity to recover PHY rate. It also improves WLAN stability at
lower RSSI without sacificing BT traffic.

Signed-off-by: Rajkumar Manoharan <[e-mail]>
Signed-off-by: John W. Linville <[e-mail]>

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

···
 	int rssi_count;
 	struct ath_gen_timer *no_stomp_timer; /* Timer for no BT stomping */
 	struct ath_mci_profile mci;
+	u8 stomp_audio;
 };
 
 #ifdef CONFIG_ATH9K_BTCOEX_SUPPORT

drivers/net/wireless/ath/ath9k/btcoex.c

···
 	{ 0x01017d01, 0x3b3b3b01, 0x3b3b3b01, 0x3b3b3b3b }, /* STOMP_LOW */
 	{ 0x01017d01, 0x01010101, 0x01010101, 0x01010101 }, /* STOMP_NONE */
 	{ 0x01017d01, 0x013b0101, 0x3b3b0101, 0x3b3b013b }, /* STOMP_LOW_FTP */
+	{ 0xffffff01, 0xffffffff, 0xffffff01, 0xffffffff }, /* STOMP_AUDIO */
 };
 
 void ath9k_hw_init_btcoex_hw(struct ath_hw *ah, int qnum)

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

···
 	ATH_BTCOEX_STOMP_LOW,
 	ATH_BTCOEX_STOMP_NONE,
 	ATH_BTCOEX_STOMP_LOW_FTP,
+	ATH_BTCOEX_STOMP_AUDIO,
 	ATH_BTCOEX_STOMP_MAX
 };
 

drivers/net/wireless/ath/ath9k/gpio.c

···
 			stomp_type = ATH_BTCOEX_STOMP_ALL;
 			timer_period = btcoex->btscan_no_stomp;
 		}
+	} else if (btcoex->stomp_audio >= 5) {
+		stomp_type = ATH_BTCOEX_STOMP_AUDIO;
+		btcoex->stomp_audio = 0;
 	}
 
 	ath9k_hw_btcoex_bt_stomp(ah, stomp_type);
···
 	    (!(ah->caps.hw_caps & ATH9K_HW_CAP_MCI) &&
 	     test_bit(BT_OP_SCAN, &btcoex->op_flags)))
 		ath9k_hw_btcoex_bt_stomp(ah, ATH_BTCOEX_STOMP_NONE);
-	 else if (btcoex->bt_stomp_type == ATH_BTCOEX_STOMP_ALL)
+	else if (btcoex->bt_stomp_type == ATH_BTCOEX_STOMP_ALL)
 		ath9k_hw_btcoex_bt_stomp(ah, ATH_BTCOEX_STOMP_LOW);
 
 	ath9k_hw_btcoex_enable(ah);

drivers/net/wireless/ath/ath9k/mci.c

···
 		ath9k_hw_set_txpowerlimit(ah, sc->config.txpowlimit, false);
 }
 
+static void ath9k_mci_stomp_audio(struct ath_softc *sc)
+{
+	struct ath_hw *ah = sc->sc_ah;
+	struct ath_btcoex *btcoex = &sc->btcoex;
+	struct ath_mci_profile *mci = &btcoex->mci;
+
+	if (!mci->num_sco && !mci->num_a2dp)
+		return;
+
+	if (ah->stats.avgbrssi > 25) {
+		btcoex->stomp_audio = 0;
+		return;
+	}
+
+	btcoex->stomp_audio++;
+}
 void ath9k_mci_update_rssi(struct ath_softc *sc)
 {
 	struct ath_hw *ah = sc->sc_ah;
 	struct ath_btcoex *btcoex = &sc->btcoex;
 	struct ath9k_hw_mci *mci_hw = &sc->sc_ah->btcoex_hw.mci;
+
+	ath9k_mci_stomp_audio(sc);
 
 	if (!(mci_hw->config & ATH_MCI_CONFIG_CONCUR_TX))
 		return;