ath9k: add stability fixes for long standing hang issues (FS#13, #34, #373, #383)

The radio would stop communicating completely. This issue was easiest to
trigger on AR913x devices, e.g. the TP-Link TL-WR1043ND, but other
hardware was occasionally affected as well.

The most critical issue was a race condition in disabling/enabling IRQs
between the IRQ handler and the IRQ processing tasklet

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

1 files changed, 100 insertions, 0 deletions

diff --git a/package/kernel/mac80211/patches/356-ath9k-check-for-deaf-rx-path-state.patch b/package/kernel/mac80211/patches/356-ath9k-check-for-deaf-rx-path-state.patch
new file mode 100644
index 0000000000..347d06ec88
--- /dev/null
+++ b/package/kernel/mac80211/patches/356-ath9k-check-for-deaf-rx-path-state.patch
@@ -0,0 +1,100 @@
+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) {