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ath9k: content DMA start / stop through the PCU lock
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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@candelatech.com>
Cc: Kyungwan Nam <kyungwan.nam@atheros.com>
Cc: stable@kernel.org
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
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Luis R. Rodriguez authored and John W. Linville committed Nov 15, 2010
1 parent 4bdd1e9 commit 6a6733f
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Showing 2 changed files with 26 additions and 28 deletions.
52 changes: 26 additions & 26 deletions drivers/net/wireless/ath/ath9k/main.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -230,6 +230,8 @@ 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.
Expand All @@ -242,8 +244,6 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
ath9k_hw_disable_interrupts(ah);
ath_drain_all_txq(sc, false);

spin_lock_bh(&sc->sc_pcu_lock);

stopped = ath_stoprecv(sc);

/* XXX: do not flush receive queue here. We don't want
Expand All @@ -268,20 +268,16 @@ 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;
}

if (ath_startrecv(sc) != 0) {
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);

Expand All @@ -292,6 +288,8 @@ 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;
}
Expand Down Expand Up @@ -605,6 +603,8 @@ 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);

Expand All @@ -615,15 +615,12 @@ 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) {
Expand All @@ -649,6 +646,8 @@ void ath9k_tasklet(unsigned long data)

/* re-enable hardware interrupt */
ath9k_hw_enable_interrupts(ah);

spin_unlock_bh(&sc->sc_pcu_lock);
ath9k_ps_restore(sc);
}

Expand Down Expand Up @@ -876,12 +875,13 @@ 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,
Expand All @@ -897,8 +897,6 @@ 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 */

Expand All @@ -911,6 +909,8 @@ 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);
}

Expand All @@ -921,6 +921,8 @@ 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);

/*
Expand All @@ -937,8 +939,6 @@ 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 */

Expand All @@ -955,10 +955,11 @@ 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);
}

Expand All @@ -972,13 +973,13 @@ 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_disable_interrupts(ah);
ath_drain_all_txq(sc, retry_tx);

spin_lock_bh(&sc->sc_pcu_lock);

ath_stoprecv(sc);
ath_flushrecv(sc);

Expand All @@ -991,8 +992,6 @@ 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
Expand All @@ -1017,6 +1016,7 @@ 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);
Expand Down Expand Up @@ -1381,25 +1381,25 @@ 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_disable_interrupts(ah);

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);

/* Finally, put the chip in FULL SLEEP mode */
Expand Down
2 changes: 0 additions & 2 deletions drivers/net/wireless/ath/ath9k/xmit.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1148,13 +1148,11 @@ void ath_drain_all_txq(struct ath_softc *sc, bool retry_tx)
ath_print(common, ATH_DBG_FATAL,
"Failed to stop TX DMA. Resetting hardware!\n");

spin_lock_bh(&sc->sc_pcu_lock);
r = ath9k_hw_reset(ah, sc->sc_ah->curchan, ah->caldata, false);
if (r)
ath_print(common, ATH_DBG_FATAL,
"Unable to reset hardware; reset status %d\n",
r);
spin_unlock_bh(&sc->sc_pcu_lock);
}

for (i = 0; i < ATH9K_NUM_TX_QUEUES; i++) {
Expand Down

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