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[PATCH 3/9] ath9k: content DMA start / stop through the PCU lock

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commit 6a6733f256f18cbcf4875e13f59eedb593b755a8 upstream

This helps align resets / RX enable & disable / TX stop / start.
Locking around the PCU is important to ensure the hardware doesn't
get stale data when working with DMA'able data.

This is part of a series of patches which fix stopping
TX DMA completley when requested on the driver.
For more details about this issue refer to this thread:

http://marc.info/?l=linux-wireless&m=128629803703756&w=2

Tested-by:  Ben Greear <greearb@xxxxxxxxxxxxxxx>
Cc: Kyungwan Nam <kyungwan.nam@xxxxxxxxxxx>
Cc: stable@xxxxxxxxxx
Signed-off-by: Luis R. Rodriguez <lrodriguez@xxxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
---
 drivers/net/wireless/ath/ath9k/main.c |   52 ++++++++++++++++----------------
 1 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 5e3e979..5a5f59f 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -234,6 +234,8 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
 
 	ath9k_ps_wakeup(sc);
 
+	spin_lock_bh(&sc->sc_pcu_lock);
+
 	/*
 	 * This is only performed if the channel settings have
 	 * actually changed.
@@ -246,8 +248,6 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
 	ath9k_hw_set_interrupts(ah, 0);
 	stopped = ath_drain_all_txq(sc, false);
 
-	spin_lock_bh(&sc->sc_pcu_lock);
-
 	if (!ath_stoprecv(sc))
 		stopped = false;
 
@@ -273,7 +273,6 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
 			  "Unable to reset channel (%u MHz), "
 			  "reset status %d\n",
 			  channel->center_freq, r);
-		spin_unlock_bh(&sc->sc_pcu_lock);
 		goto ps_restore;
 	}
 
@@ -281,12 +280,9 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
 		ath_print(common, ATH_DBG_FATAL,
 			  "Unable to restart recv logic\n");
 		r = -EIO;
-		spin_unlock_bh(&sc->sc_pcu_lock);
 		goto ps_restore;
 	}
 
-	spin_unlock_bh(&sc->sc_pcu_lock);
-
 	ath_update_txpow(sc);
 	ath9k_hw_set_interrupts(ah, ah->imask);
 
@@ -298,6 +294,8 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
 	}
 
  ps_restore:
+	spin_unlock_bh(&sc->sc_pcu_lock);
+
 	ath9k_ps_restore(sc);
 	return r;
 }
@@ -612,6 +610,8 @@ void ath9k_tasklet(unsigned long data)
 		return;
 	}
 
+	spin_lock_bh(&sc->sc_pcu_lock);
+
 	if (!ath9k_hw_check_alive(ah))
 		ieee80211_queue_work(sc->hw, &sc->hw_check_work);
 
@@ -622,15 +622,12 @@ void ath9k_tasklet(unsigned long data)
 		rxmask = (ATH9K_INT_RX | ATH9K_INT_RXEOL | ATH9K_INT_RXORN);
 
 	if (status & rxmask) {
-		spin_lock_bh(&sc->sc_pcu_lock);
-
 		/* Check for high priority Rx first */
 		if ((ah->caps.hw_caps & ATH9K_HW_CAP_EDMA) &&
 		    (status & ATH9K_INT_RXHP))
 			ath_rx_tasklet(sc, 0, true);
 
 		ath_rx_tasklet(sc, 0, false);
-		spin_unlock_bh(&sc->sc_pcu_lock);
 	}
 
 	if (status & ATH9K_INT_TX) {
@@ -656,6 +653,8 @@ void ath9k_tasklet(unsigned long data)
 
 	/* re-enable hardware interrupt */
 	ath9k_hw_set_interrupts(ah, ah->imask);
+
+	spin_unlock_bh(&sc->sc_pcu_lock);
 	ath9k_ps_restore(sc);
 }
 
@@ -880,12 +879,13 @@ void ath_radio_enable(struct ath_softc *sc, struct ieee80211_hw *hw)
 	int r;
 
 	ath9k_ps_wakeup(sc);
+	spin_lock_bh(&sc->sc_pcu_lock);
+
 	ath9k_hw_configpcipowersave(ah, 0, 0);
 
 	if (!ah->curchan)
 		ah->curchan = ath_get_curchannel(sc, sc->hw);
 
-	spin_lock_bh(&sc->sc_pcu_lock);
 	r = ath9k_hw_reset(ah, ah->curchan, ah->caldata, false);
 	if (r) {
 		ath_print(common, ATH_DBG_FATAL,
@@ -901,8 +901,6 @@ void ath_radio_enable(struct ath_softc *sc, struct ieee80211_hw *hw)
 		spin_unlock_bh(&sc->sc_pcu_lock);
 		return;
 	}
-	spin_unlock_bh(&sc->sc_pcu_lock);
-
 	if (sc->sc_flags & SC_OP_BEACONS)
 		ath_beacon_config(sc, NULL);	/* restart beacons */
 
@@ -915,6 +913,8 @@ void ath_radio_enable(struct ath_softc *sc, struct ieee80211_hw *hw)
 	ath9k_hw_set_gpio(ah, ah->led_pin, 0);
 
 	ieee80211_wake_queues(hw);
+	spin_unlock_bh(&sc->sc_pcu_lock);
+
 	ath9k_ps_restore(sc);
 }
 
@@ -925,6 +925,8 @@ void ath_radio_disable(struct ath_softc *sc, struct ieee80211_hw *hw)
 	int r;
 
 	ath9k_ps_wakeup(sc);
+	spin_lock_bh(&sc->sc_pcu_lock);
+
 	ieee80211_stop_queues(hw);
 
 	/*
@@ -941,8 +943,6 @@ void ath_radio_disable(struct ath_softc *sc, struct ieee80211_hw *hw)
 
 	ath_drain_all_txq(sc, false);	/* clear pending tx frames */
 
-	spin_lock_bh(&sc->sc_pcu_lock);
-
 	ath_stoprecv(sc);		/* turn off frame recv */
 	ath_flushrecv(sc);		/* flush recv queue */
 
@@ -959,10 +959,11 @@ void ath_radio_disable(struct ath_softc *sc, struct ieee80211_hw *hw)
 
 	ath9k_hw_phy_disable(ah);
 
-	spin_unlock_bh(&sc->sc_pcu_lock);
-
 	ath9k_hw_configpcipowersave(ah, 1, 1);
+
+	spin_unlock_bh(&sc->sc_pcu_lock);
 	ath9k_ps_restore(sc);
+
 	ath9k_setpower(sc, ATH9K_PM_FULL_SLEEP);
 }
 
@@ -976,13 +977,13 @@ int ath_reset(struct ath_softc *sc, bool retry_tx)
 	/* Stop ANI */
 	del_timer_sync(&common->ani.timer);
 
+	spin_lock_bh(&sc->sc_pcu_lock);
+
 	ieee80211_stop_queues(hw);
 
 	ath9k_hw_set_interrupts(ah, 0);
 	ath_drain_all_txq(sc, retry_tx);
 
-	spin_lock_bh(&sc->sc_pcu_lock);
-
 	ath_stoprecv(sc);
 	ath_flushrecv(sc);
 
@@ -995,8 +996,6 @@ int ath_reset(struct ath_softc *sc, bool retry_tx)
 		ath_print(common, ATH_DBG_FATAL,
 			  "Unable to start recv logic\n");
 
-	spin_unlock_bh(&sc->sc_pcu_lock);
-
 	/*
 	 * We may be doing a reset in response to a request
 	 * that changes the channel so update any state that
@@ -1021,6 +1020,7 @@ int ath_reset(struct ath_softc *sc, bool retry_tx)
 	}
 
 	ieee80211_wake_queues(hw);
+	spin_unlock_bh(&sc->sc_pcu_lock);
 
 	/* Start ANI */
 	ath_start_ani(common);
@@ -1386,25 +1386,25 @@ static void ath9k_stop(struct ieee80211_hw *hw)
 			ath9k_btcoex_timer_pause(sc);
 	}
 
+	spin_lock_bh(&sc->sc_pcu_lock);
+
 	/* make sure h/w will not generate any interrupt
 	 * before setting the invalid flag. */
 	ath9k_hw_set_interrupts(ah, 0);
 
 	if (!(sc->sc_flags & SC_OP_INVALID)) {
 		ath_drain_all_txq(sc, false);
-		spin_lock_bh(&sc->sc_pcu_lock);
 		ath_stoprecv(sc);
 		ath9k_hw_phy_disable(ah);
-		spin_unlock_bh(&sc->sc_pcu_lock);
-	} else {
-		spin_lock_bh(&sc->sc_pcu_lock);
+	} else
 		sc->rx.rxlink = NULL;
-		spin_unlock_bh(&sc->sc_pcu_lock);
-	}
 
 	/* disable HAL and put h/w to sleep */
 	ath9k_hw_disable(ah);
 	ath9k_hw_configpcipowersave(ah, 1, 1);
+
+	spin_unlock_bh(&sc->sc_pcu_lock);
+
 	ath9k_ps_restore(sc);
 
 	sc->ps_idle = true;
-- 
1.7.4.15.g7811d

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