ath9k: recover ar9380 chips from rare stuck state

In the experiment with Azimuth ADEPT-n testbed where the APs transmit
power was reduced to 25% and the signal strength was futher attenuated
by 20dB and induced a path loss of ~7dB, the station was reporting
beacon losses and the following issue were observed.

* rx clear is stuck at low for more than 300ms
* dcu chain and complete state is stuck at one of the hang signature

This patch triggers the hang detection logic that recovers the chip
from any of the above conditions. As the issue was originally reported
in ChromeOs with AR9382 chips, this detection logic is enabled only for
AR9380/2 chips.

Cc: Paul Stewart <pstew@google.com>
Reported-by: Gary Morain <gmorain@google.com>
Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 44 insertions, 4 deletions

diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 38794850f00..eeea81b16d9 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -243,6 +243,7 @@ static bool ath_prepare_reset(struct ath_softc *sc, bool retry_tx, bool flush)
 
 	sc->hw_busy_count = 0;
 	del_timer_sync(&common->ani.timer);
+	del_timer_sync(&sc->rx_poll_timer);
 
 	ath9k_debug_samp_bb_mac(sc);
 	ath9k_hw_disable_interrupts(ah);
@@ -284,6 +285,7 @@ static bool ath_complete_reset(struct ath_softc *sc, bool start)
 
 		ieee80211_queue_delayed_work(sc->hw, &sc->tx_complete_work, 0);
 		ieee80211_queue_delayed_work(sc->hw, &sc->hw_pll_work, HZ/2);
+		ath_start_rx_poll(sc, 3);
 		if (!common->disable_ani)
 			ath_start_ani(common);
 	}
@@ -914,10 +916,19 @@ void ath_hw_check(struct work_struct *work)
 	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
 	unsigned long flags;
 	int busy;
+	u8 is_alive, nbeacon = 1;
 
 	ath9k_ps_wakeup(sc);
-	if (ath9k_hw_check_alive(sc->sc_ah))
+	is_alive = ath9k_hw_check_alive(sc->sc_ah);
+
+	if (is_alive && !AR_SREV_9300(sc->sc_ah))
 		goto out;
+	else if (!is_alive && AR_SREV_9300(sc->sc_ah)) {
+		ath_dbg(common, RESET,
+			"DCU stuck is detected. Schedule chip reset\n");
+		RESET_STAT_INC(sc, RESET_TYPE_MAC_HANG);
+		goto sched_reset;
+	}
 
 	spin_lock_irqsave(&common->cc_lock, flags);
 	busy = ath_update_survey_stats(sc);
@@ -928,12 +939,18 @@ void ath_hw_check(struct work_struct *work)
 	if (busy >= 99) {
 		if (++sc->hw_busy_count >= 3) {
 			RESET_STAT_INC(sc, RESET_TYPE_BB_HANG);
-			ieee80211_queue_work(sc->hw, &sc->hw_reset_work);
+			goto sched_reset;
 		}
-
-	} else if (busy >= 0)
+	} else if (busy >= 0) {
 		sc->hw_busy_count = 0;
+		nbeacon = 3;
+	}
 
+	ath_start_rx_poll(sc, nbeacon);
+	goto out;
+
+sched_reset:
+	ieee80211_queue_work(sc->hw, &sc->hw_reset_work);
 out:
 	ath9k_ps_restore(sc);
 }
@@ -1153,6 +1170,7 @@ static void ath9k_stop(struct ieee80211_hw *hw)
 	mutex_lock(&sc->mutex);
 
 	ath_cancel_work(sc);
+	del_timer_sync(&sc->rx_poll_timer);
 
 	if (sc->sc_flags & SC_OP_INVALID) {
 		ath_dbg(common, ANY, "Device not present\n");
@@ -1385,6 +1403,24 @@ static void ath9k_do_vif_add_setup(struct ieee80211_hw *hw,
 	}
 }
 
+void ath_start_rx_poll(struct ath_softc *sc, u8 nbeacon)
+{
+	if (!AR_SREV_9300(sc->sc_ah))
+		return;
+
+	if (!(sc->sc_flags & SC_OP_PRIM_STA_VIF))
+		return;
+
+	mod_timer(&sc->rx_poll_timer, jiffies + msecs_to_jiffies
+			(nbeacon * sc->cur_beacon_conf.beacon_interval));
+}
+
+void ath_rx_poll(unsigned long data)
+{
+	struct ath_softc *sc = (struct ath_softc *)data;
+
+	ieee80211_queue_work(sc->hw, &sc->hw_check_work);
+}
 
 static int ath9k_add_interface(struct ieee80211_hw *hw,
 			       struct ieee80211_vif *vif)
@@ -1906,6 +1942,8 @@ static void ath9k_bss_iter(void *data, u8 *mac, struct ieee80211_vif *vif)
 		sc->last_rssi = ATH_RSSI_DUMMY_MARKER;
 		sc->sc_ah->stats.avgbrssi = ATH_RSSI_DUMMY_MARKER;
 
+		ath_start_rx_poll(sc, 3);
+
 		if (!common->disable_ani) {
 			sc->sc_flags |= SC_OP_ANI_RUN;
 			ath_start_ani(common);
@@ -1945,6 +1983,7 @@ static void ath9k_config_bss(struct ath_softc *sc, struct ieee80211_vif *vif)
 		/* Stop ANI */
 		sc->sc_flags &= ~SC_OP_ANI_RUN;
 		del_timer_sync(&common->ani.timer);
+		del_timer_sync(&sc->rx_poll_timer);
 		memset(&sc->caldata, 0, sizeof(sc->caldata));
 	}
 }
@@ -1988,6 +2027,7 @@ static void ath9k_bss_info_changed(struct ieee80211_hw *hw,
 		} else {
 			sc->sc_flags &= ~SC_OP_ANI_RUN;
 			del_timer_sync(&common->ani.timer);
+			del_timer_sync(&sc->rx_poll_timer);
 		}
 	}