From: Felix Fietkau <nbd@nbd.name>
Date: Wed, 25 Jan 2017 13:00:58 +0100
Subject: [PATCH] ath9k: check for deaf rx path state

Various chips occasionally run into a state where the tx path still
appears to be working normally, but the rx path is deaf.

There is no known register signature to check for this state explicitly,
so use the lack of rx interrupts as an indicator.

This detection is prone to false positives, since a device could also
simply be in an environment where there are no frames on the air.
However, in this case doing a reset should be harmless since it's
obviously not interrupting any real activity. To avoid confusion, call
the reset counters in this case "Rx path inactive" instead of something
like "Rx path deaf", since it may not be an indication of a real
hardware failure.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -1027,6 +1027,7 @@ struct ath_softc {
 
 	u8 gtt_cnt;
 	u32 intrstatus;
+	u32 rx_active;
 	u16 ps_flags; /* PS_* */
 	bool ps_enabled;
 	bool ps_idle;
--- a/drivers/net/wireless/ath/ath9k/debug.c
+++ b/drivers/net/wireless/ath/ath9k/debug.c
@@ -763,6 +763,7 @@ static int read_file_reset(struct seq_fi
 		[RESET_TYPE_BEACON_STUCK] = "Stuck Beacon",
 		[RESET_TYPE_MCI] = "MCI Reset",
 		[RESET_TYPE_CALIBRATION] = "Calibration error",
+		[RESET_TYPE_RX_INACTIVE] = "Rx path inactive",
 		[RESET_TX_DMA_ERROR] = "Tx DMA stop error",
 		[RESET_RX_DMA_ERROR] = "Rx DMA stop error",
 	};
--- a/drivers/net/wireless/ath/ath9k/debug.h
+++ b/drivers/net/wireless/ath/ath9k/debug.h
@@ -50,6 +50,7 @@ enum ath_reset_type {
 	RESET_TYPE_BEACON_STUCK,
 	RESET_TYPE_MCI,
 	RESET_TYPE_CALIBRATION,
+	RESET_TYPE_RX_INACTIVE,
 	RESET_TX_DMA_ERROR,
 	RESET_RX_DMA_ERROR,
 	__RESET_TYPE_MAX
--- a/drivers/net/wireless/ath/ath9k/link.c
+++ b/drivers/net/wireless/ath/ath9k/link.c
@@ -53,13 +53,27 @@ reset:
 
 }
 
+static bool ath_rx_active_check(struct ath_softc *sc)
+{
+	if (sc->rx_active) {
+		sc->rx_active = 0;
+		return true;
+	}
+
+	ath_dbg(ath9k_hw_common(sc->sc_ah), RESET,
+		"rx path inactive, resetting the chip\n");
+	ath9k_queue_reset(sc, RESET_TYPE_RX_INACTIVE);
+	return false;
+}
+
 void ath_hw_check_work(struct work_struct *work)
 {
 	struct ath_softc *sc = container_of(work, struct ath_softc,
 					    hw_check_work.work);
 
 	if (!ath_hw_check(sc) ||
-	    !ath_tx_complete_check(sc))
+	    !ath_tx_complete_check(sc) ||
+	    !ath_rx_active_check(sc))
 		return;
 
 	ieee80211_queue_delayed_work(sc->hw, &sc->hw_check_work,
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -269,6 +269,7 @@ static bool ath_complete_reset(struct at
 	}
 
 	sc->gtt_cnt = 0;
+	sc->rx_active = 1;
 
 	ath9k_hw_set_interrupts(ah);
 	ath9k_hw_enable_interrupts(ah);
@@ -452,6 +453,7 @@ void ath9k_tasklet(unsigned long data)
 			ath_rx_tasklet(sc, 0, true);
 
 		ath_rx_tasklet(sc, 0, false);
+		sc->rx_active = 1;
 	}
 
 	if (status & ATH9K_INT_TX) {