ath9k: Fix a PLL hang issue observed with AR9485.

When this PLL hang issue is seen, both Rx and Tx fail to work.
The sqsum_dvc needs to be below 2000 for a good chip. During
this issue the sqsum_dvc value is beyond 80000 and only a
full reset can solve this problem.

Signed-off-by: Vivek Natarajan <vnatarajan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 27 insertions, 0 deletions

diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index 73db9576af57..a23e9a884693 100644
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -641,6 +641,7 @@ struct ath_softc {
 #endif
         struct ath_beacon_config cur_beacon_conf;
         struct delayed_work tx_complete_work;
+        struct delayed_work hw_pll_work;
         struct ath_btcoex btcoex;
 
         struct ath_descdma txsdma;
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 23c016a81bcf..0663a32d81d2 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -230,6 +230,7 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
         cancel_work_sync(&sc->paprd_work);
         cancel_work_sync(&sc->hw_check_work);
         cancel_delayed_work_sync(&sc->tx_complete_work);
+        cancel_delayed_work_sync(&sc->hw_pll_work);
 
         ath9k_ps_wakeup(sc);
 
@@ -290,6 +291,7 @@ int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
                 if (sc->sc_flags & SC_OP_BEACONS)
                         ath_beacon_config(sc, NULL);
                 ieee80211_queue_delayed_work(sc->hw, &sc->tx_complete_work, 0);
+                ieee80211_queue_delayed_work(sc->hw, &sc->hw_pll_work, HZ/2);
                 ath_start_ani(common);
         }
 
@@ -1263,6 +1265,7 @@ static void ath9k_stop(struct ieee80211_hw *hw)
                 cancel_delayed_work_sync(&sc->ath_led_blink_work);
 
         cancel_delayed_work_sync(&sc->tx_complete_work);
+        cancel_delayed_work_sync(&sc->hw_pll_work);
         cancel_work_sync(&sc->paprd_work);
         cancel_work_sync(&sc->hw_check_work);
 
diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 879365e9b1c9..10a3dbefaa09 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -2091,6 +2091,28 @@ static void ath_tx_processq(struct ath_softc *sc, struct ath_txq *txq)
         }
 }
 
+static void ath_hw_pll_work(struct work_struct *work)
+{
+        struct ath_softc *sc = container_of(work, struct ath_softc,
+                                            hw_pll_work.work);
+        static int count;
+
+        if (AR_SREV_9485(sc->sc_ah)) {
+                if (ar9003_get_pll_sqsum_dvc(sc->sc_ah) >= 0x40000) {
+                        count++;
+
+                        if (count == 3) {
+                                /* Rx is hung for more than 500ms. Reset it */
+                                ath_reset(sc, true);
+                                count = 0;
+                        }
+                } else
+                        count = 0;
+
+                ieee80211_queue_delayed_work(sc->hw, &sc->hw_pll_work, HZ/5);
+        }
+}
+
 static void ath_tx_complete_poll_work(struct work_struct *work)
 {
         struct ath_softc *sc = container_of(work, struct ath_softc,
@@ -2312,6 +2334,7 @@ int ath_tx_init(struct ath_softc *sc, int nbufs)
         }
 
         INIT_DELAYED_WORK(&sc->tx_complete_work, ath_tx_complete_poll_work);
+        INIT_DELAYED_WORK(&sc->hw_pll_work, ath_hw_pll_work);
 
         if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA) {
                 error = ath_tx_edma_init(sc);