ath9k: Update Beacon timers based on timestamp from the AP

Some APs seem to drift away from the expected TBTT (timestamp %
beacon_int_in_usec differs quite a bit from zero) which can result in
us waking up way too early to receive a Beacon frame. In order to work
around this, re-configure the Beacon timers after having received a
Beacon frame from the AP (i.e., when we know the offset between the
expected TBTT and the actual time the AP is sending out the Beacon
frame).

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

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 5e046b58ad93..5014a19b0f75 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -521,6 +521,13 @@ static void ath_rx_ps_beacon(struct ath_softc *sc, struct sk_buff *skb)
         if (memcmp(sc->curbssid, mgmt->bssid, ETH_ALEN) != 0)
                 return; /* not from our current AP */
 
+        if (sc->sc_flags & SC_OP_BEACON_SYNC) {
+                sc->sc_flags &= ~SC_OP_BEACON_SYNC;
+                DPRINTF(sc, ATH_DBG_PS, "Reconfigure Beacon timers based on "
+                        "timestamp from the AP\n");
+                ath_beacon_config(sc, NULL);
+        }
+
         if (!(sc->hw->conf.flags & IEEE80211_CONF_PS)) {
                 /* We are not in PS mode anymore; remain awake */
                 DPRINTF(sc, ATH_DBG_PS, "Not in PS mode anymore, remain "