ath9k: Fix wifi disconnection when collocated bt scan is active

As all bt packets are priority traffic during bt scan, wifi
will get disconnected when bt scan lasts for few seconds. Fix
this by allocating 10% of bt period time (4.5ms) to wifi fully.

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

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

@@ -364,6 +364,7 @@ struct ath_btcoex {
 	int bt_stomp_type; /* Types of BT stomping */
 	u32 btcoex_no_stomp; /* in usec */
 	u32 btcoex_period; /* in usec */
+	u32 btscan_no_stomp; /* in usec */
 	struct ath_gen_timer *no_stomp_timer; /* Timer for no BT stomping */
 };
 
@@ -429,6 +430,7 @@ void ath_deinit_leds(struct ath_softc *sc);
 #define SC_OP_SCANNING               BIT(10)
 #define SC_OP_TSF_RESET              BIT(11)
 #define SC_OP_BT_PRIORITY_DETECTED   BIT(12)
+#define SC_OP_BT_SCAN		     BIT(13)
 
 /* Powersave flags */
 #define PS_WAIT_FOR_BEACON        BIT(0)

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

@@ -25,10 +25,12 @@
 
 #define ATH_BTCOEX_DEF_BT_PERIOD  45
 #define ATH_BTCOEX_DEF_DUTY_CYCLE 55
+#define ATH_BTCOEX_BTSCAN_DUTY_CYCLE 90
 #define ATH_BTCOEX_BMISS_THRESH   50
 
 #define ATH_BT_PRIORITY_TIME_THRESHOLD 1000 /* ms */
 #define ATH_BT_CNT_THRESHOLD	       3
+#define ATH_BT_CNT_SCAN_THRESHOLD      15
 
 enum ath_btcoex_scheme {
 	ATH_BTCOEX_CFG_NONE,

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

@@ -230,12 +230,17 @@ static void ath_detect_bt_priority(struct ath_softc *sc)
 
 	if (time_after(jiffies, btcoex->bt_priority_time +
 			msecs_to_jiffies(ATH_BT_PRIORITY_TIME_THRESHOLD))) {
-		if (btcoex->bt_priority_cnt >= ATH_BT_CNT_THRESHOLD) {
+		sc->sc_flags &= ~(SC_OP_BT_PRIORITY_DETECTED | SC_OP_BT_SCAN);
+		/* Detect if colocated bt started scanning */
+		if (btcoex->bt_priority_cnt >= ATH_BT_CNT_SCAN_THRESHOLD) {
+			ath_print(ath9k_hw_common(sc->sc_ah), ATH_DBG_BTCOEX,
+				  "BT scan detected");
+			sc->sc_flags |= (SC_OP_BT_SCAN |
+					 SC_OP_BT_PRIORITY_DETECTED);
+		} else if (btcoex->bt_priority_cnt >= ATH_BT_CNT_THRESHOLD) {
 			ath_print(ath9k_hw_common(sc->sc_ah), ATH_DBG_BTCOEX,
 				  "BT priority traffic detected");
 			sc->sc_flags |= SC_OP_BT_PRIORITY_DETECTED;
-		} else {
-			sc->sc_flags &= ~SC_OP_BT_PRIORITY_DETECTED;
 		}
 
 		btcoex->bt_priority_cnt = 0;
@@ -316,12 +321,17 @@ static void ath_btcoex_period_timer(unsigned long data)
 	struct ath_softc *sc = (struct ath_softc *) data;
 	struct ath_hw *ah = sc->sc_ah;
 	struct ath_btcoex *btcoex = &sc->btcoex;
+	u32 timer_period;
+	bool is_btscan;
 
 	ath_detect_bt_priority(sc);
 
+	is_btscan = sc->sc_flags & SC_OP_BT_SCAN;
+
 	spin_lock_bh(&btcoex->btcoex_lock);
 
-	ath9k_btcoex_bt_stomp(sc, btcoex->bt_stomp_type);
+	ath9k_btcoex_bt_stomp(sc, is_btscan ? ATH_BTCOEX_STOMP_ALL :
+			      btcoex->bt_stomp_type);
 
 	spin_unlock_bh(&btcoex->btcoex_lock);
 
@@ -329,11 +339,12 @@ static void ath_btcoex_period_timer(unsigned long data)
 		if (btcoex->hw_timer_enabled)
 			ath9k_gen_timer_stop(ah, btcoex->no_stomp_timer);
 
+		timer_period = is_btscan ? btcoex->btscan_no_stomp :
+					   btcoex->btcoex_no_stomp;
 		ath9k_gen_timer_start(ah,
 				      btcoex->no_stomp_timer,
 				      (ath9k_hw_gettsf32(ah) +
-				       btcoex->btcoex_no_stomp),
-				       btcoex->btcoex_no_stomp * 10);
+				       timer_period), timer_period * 10);
 		btcoex->hw_timer_enabled = true;
 	}
 
@@ -350,13 +361,14 @@ static void ath_btcoex_no_stomp_timer(void *arg)
 	struct ath_softc *sc = (struct ath_softc *)arg;
 	struct ath_hw *ah = sc->sc_ah;
 	struct ath_btcoex *btcoex = &sc->btcoex;
+	bool is_btscan = sc->sc_flags & SC_OP_BT_SCAN;
 
 	ath_print(ath9k_hw_common(ah), ATH_DBG_BTCOEX,
 		  "no stomp timer running \n");
 
 	spin_lock_bh(&btcoex->btcoex_lock);
 
-	if (btcoex->bt_stomp_type == ATH_BTCOEX_STOMP_LOW)
+	if (btcoex->bt_stomp_type == ATH_BTCOEX_STOMP_LOW || is_btscan)
 		ath9k_btcoex_bt_stomp(sc, ATH_BTCOEX_STOMP_NONE);
 	 else if (btcoex->bt_stomp_type == ATH_BTCOEX_STOMP_ALL)
 		ath9k_btcoex_bt_stomp(sc, ATH_BTCOEX_STOMP_LOW);
@@ -371,6 +383,8 @@ int ath_init_btcoex_timer(struct ath_softc *sc)
 	btcoex->btcoex_period = ATH_BTCOEX_DEF_BT_PERIOD * 1000;
 	btcoex->btcoex_no_stomp = (100 - ATH_BTCOEX_DEF_DUTY_CYCLE) *
 		btcoex->btcoex_period / 100;
+	btcoex->btscan_no_stomp = (100 - ATH_BTCOEX_BTSCAN_DUTY_CYCLE) *
+				   btcoex->btcoex_period / 100;
 
 	setup_timer(&btcoex->period_timer, ath_btcoex_period_timer,
 			(unsigned long) sc);
@@ -405,7 +419,7 @@ void ath9k_btcoex_timer_resume(struct ath_softc *sc)
 
 	btcoex->bt_priority_cnt = 0;
 	btcoex->bt_priority_time = jiffies;
-	sc->sc_flags &= ~SC_OP_BT_PRIORITY_DETECTED;
+	sc->sc_flags &= ~(SC_OP_BT_PRIORITY_DETECTED | SC_OP_BT_SCAN);
 
 	mod_timer(&btcoex->period_timer, jiffies);
 }

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

@@ -1547,9 +1547,9 @@ enum {
 
 #define AR_BT_COEX_WEIGHT          0x8174
 #define AR_BT_COEX_WGHT		   0xff55
-#define AR_STOMP_ALL_WLAN_WGHT	   0xffcc
-#define AR_STOMP_LOW_WLAN_WGHT	   0xaaa8
-#define AR_STOMP_NONE_WLAN_WGHT	   0xaa00
+#define AR_STOMP_ALL_WLAN_WGHT	   0xfcfc
+#define AR_STOMP_LOW_WLAN_WGHT	   0xa8a8
+#define AR_STOMP_NONE_WLAN_WGHT	   0x0000
 #define AR_BTCOEX_BT_WGHT          0x0000ffff
 #define AR_BTCOEX_BT_WGHT_S        0
 #define AR_BTCOEX_WL_WGHT          0xffff0000