ath9k: fix TSF offset precision issue

Dividing the beacon interval by ATH_BCBUF (8) truncates the result for
the default beacon interval of 100.
Fix the calculation by moving the division after conversion from TU to
microseconds.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/net/wireless/ath/ath9k/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c
index accfb3b60daa..112aff720e13 100644
--- a/drivers/net/wireless/ath/ath9k/beacon.c
+++ b/drivers/net/wireless/ath/ath9k/beacon.c
@@ -279,13 +279,14 @@ static void ath9k_set_tsfadjust(struct ath_softc *sc, struct ieee80211_vif *vif)
         struct ath_common *common = ath9k_hw_common(sc->sc_ah);
         struct ath_beacon_config *cur_conf = &sc->cur_beacon_conf;
         struct ath_vif *avp = (void *)vif->drv_priv;
-        u64 tsfadjust;
+        u32 tsfadjust;
 
         if (avp->av_bslot == 0)
                 return;
 
-        tsfadjust = cur_conf->beacon_interval * avp->av_bslot / ATH_BCBUF;
-        avp->tsf_adjust = cpu_to_le64(TU_TO_USEC(tsfadjust));
+        tsfadjust = cur_conf->beacon_interval * avp->av_bslot;
+        tsfadjust = TU_TO_USEC(tsfadjust) / ATH_BCBUF;
+        avp->tsf_adjust = cpu_to_le64(tsfadjust);
 
         ath_dbg(common, CONFIG, "tsfadjust is: %llu for bslot: %d\n",
                 (unsigned long long)tsfadjust, avp->av_bslot);