ath9k: Add workaround to recover from failed channel changes

It looks like channel change may fail in some cases and end up leaving
the hardware in state where it cannot transmit any frames. Add a
workaround to recover from this state if we detect that wiphy
selection is failing due to wiphys not leaving PAUSING state.

Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/drivers/net/wireless/ath9k/virtual.c b/drivers/net/wireless/ath9k/virtual.c
index 6122f48f25fb..913d2043d23e 100644
--- a/drivers/net/wireless/ath9k/virtual.c
+++ b/drivers/net/wireless/ath9k/virtual.c
@@ -432,6 +432,18 @@ int ath9k_wiphy_unpause(struct ath_wiphy *aphy)
 	return ret;
 }
 
+static void __ath9k_wiphy_mark_all_paused(struct ath_softc *sc)
+{
+	int i;
+	if (sc->pri_wiphy->state != ATH_WIPHY_INACTIVE)
+		sc->pri_wiphy->state = ATH_WIPHY_PAUSED;
+	for (i = 0; i < sc->num_sec_wiphy; i++) {
+		if (sc->sec_wiphy[i] &&
+		    sc->sec_wiphy[i]->state != ATH_WIPHY_INACTIVE)
+			sc->sec_wiphy[i]->state = ATH_WIPHY_PAUSED;
+	}
+}
+
 /* caller must hold wiphy_lock */
 static void __ath9k_wiphy_pause_all(struct ath_softc *sc)
 {
@@ -452,9 +464,34 @@ int ath9k_wiphy_select(struct ath_wiphy *aphy)
 
 	spin_lock_bh(&sc->wiphy_lock);
 	if (__ath9k_wiphy_pausing(sc)) {
+		if (sc->wiphy_select_failures == 0)
+			sc->wiphy_select_first_fail = jiffies;
+		sc->wiphy_select_failures++;
+		if (time_after(jiffies, sc->wiphy_select_first_fail + HZ / 2))
+		{
+			printk(KERN_DEBUG "ath9k: Previous wiphy select timed "
+			       "out; disable/enable hw to recover\n");
+			__ath9k_wiphy_mark_all_paused(sc);
+			/*
+			 * TODO: this workaround to fix hardware is unlikely to
+			 * be specific to virtual wiphy changes. It can happen
+			 * on normal channel change, too, and as such, this
+			 * should really be made more generic. For example,
+			 * tricker radio disable/enable on GTT interrupt burst
+			 * (say, 10 GTT interrupts received without any TX
+			 * frame being completed)
+			 */
+			spin_unlock_bh(&sc->wiphy_lock);
+			ath_radio_disable(sc);
+			ath_radio_enable(sc);
+			queue_work(aphy->sc->hw->workqueue,
+				   &aphy->sc->chan_work);
+			return -EBUSY; /* previous select still in progress */
+		}
 		spin_unlock_bh(&sc->wiphy_lock);
 		return -EBUSY; /* previous select still in progress */
 	}
+	sc->wiphy_select_failures = 0;
 
 	/* Store the new channel */
 	sc->chan_idx = aphy->chan_idx;