ath9k: reduce the number of false positives triggered by the baseband hang check by only running it when beacon transmission is blocked

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@24954 3c298f89-4303-0410-b956-a3cf2f4a3e73

package/mac80211/patches/540-ath9k_bb_hang_check_fix.patch

@@ -0,0 +1,30 @@
+
+--- a/drivers/net/wireless/ath/ath9k/main.c
++++ b/drivers/net/wireless/ath/ath9k/main.c
+@@ -251,6 +251,9 @@ int ath_set_channel(struct ath_softc *sc
+ 	if (!ath_stoprecv(sc))
+ 		stopped = false;
+ 
++	if (!ath9k_hw_check_alive(ah))
++		stopped = false;
++
+ 	/* XXX: do not flush receive queue here. We don't want
+ 	 * to flush data frames already in queue because of
+ 	 * changing channel. */
+@@ -602,7 +605,15 @@ void ath9k_tasklet(unsigned long data)
+ 
+ 	spin_lock(&sc->sc_pcu_lock);
+ 
+-	if (!ath9k_hw_check_alive(ah))
++	/*
++	 * Only run the baseband hang check if beacons stop working in AP or
++	 * IBSS mode, because it has a high false positive rate. For station
++	 * mode it should not be necessary, since the upper layers will detect
++	 * this through a beacon miss automatically and the following channel
++	 * change will trigger a hardware reset anyway
++	 */
++	if (ath9k_hw_numtxpending(ah, sc->beacon.beaconq) != 0 &&
++	    !ath9k_hw_check_alive(ah))
+ 		ieee80211_queue_work(sc->hw, &sc->hw_check_work);
+ 
+ 	if (ah->caps.hw_caps & ATH9K_HW_CAP_EDMA)