This patch doesn't apply to the .37 stable tree.
If someone wants it applied there, please email the backport
to [email protected]

thanks,

greg k-h

> commit: 6a6733f256f18cbcf4875e13f59eedb593b755a8
> From: Luis R. Rodriguez <[email protected]>
> Date: Tue, 26 Oct 2010 15:27:25 -0700
> Subject: [PATCH] ath9k: content DMA start / stop through the PCU lock
> 
> 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 <[email protected]>
> Cc: Kyungwan Nam <[email protected]>
> Cc: [email protected]
> Signed-off-by: Luis R. Rodriguez <[email protected]>
> Signed-off-by: John W. Linville <[email protected]>
> ---
>  drivers/net/wireless/ath/ath9k/main.c |   52 ++++++++++++++++----------------
>  drivers/net/wireless/ath/ath9k/xmit.c |    2 -
>  2 files changed, 26 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath9k/main.c 
> b/drivers/net/wireless/ath/ath9k/main.c
> index 463ac12..d522112 100644
> --- a/drivers/net/wireless/ath/ath9k/main.c
> +++ b/drivers/net/wireless/ath/ath9k/main.c
> @@ -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.
> @@ -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
> @@ -268,7 +268,6 @@ 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;
>       }
>  
> @@ -276,12 +275,9 @@ 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);
>  
> @@ -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;
>  }
> @@ -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);
>  
> @@ -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) {
> @@ -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);
>  }
>  
> @@ -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,
> @@ -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 */
>  
> @@ -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);
>  }
>  
> @@ -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);
>  
>       /*
> @@ -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 */
>  
> @@ -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);
>  }
>  
> @@ -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);
>  
> @@ -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
> @@ -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);
> @@ -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 */
> diff --git a/drivers/net/wireless/ath/ath9k/xmit.c 
> b/drivers/net/wireless/ath/ath9k/xmit.c
> index d97b7a3..2bc422e 100644
> --- a/drivers/net/wireless/ath/ath9k/xmit.c
> +++ b/drivers/net/wireless/ath/ath9k/xmit.c
> @@ -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++) {
> 
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