ath9k: fix ad-hoc mode beacon selection

In ad-hoc mode, beacon timers are configured differently compared to AP
mode, and (depending on the scenario) can vary enough to make the beacon
tasklet not detect slot 0 based on the TSF.
Since staggered beacons are not (and cannot be) used in ad-hoc mode, it
makes more sense to just hardcode slot 0 here, avoiding unnecessary
TSF reads and calculations.

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

1 files changed, 20 insertions, 12 deletions

diff --git a/drivers/net/wireless/ath/ath9k/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c
index 637dbc5f7b67..c7f46797c75c 100644
--- a/drivers/net/wireless/ath/ath9k/beacon.c
+++ b/drivers/net/wireless/ath/ath9k/beacon.c
@@ -351,9 +351,7 @@ void ath_beacon_tasklet(unsigned long data)
         struct ath_buf *bf = NULL;
         struct ieee80211_vif *vif;
         int slot;
-        u32 bfaddr, bc = 0, tsftu;
-        u64 tsf;
-        u16 intval;
+        u32 bfaddr, bc = 0;
 
         /*
          * Check if the previous beacon has gone out.  If
@@ -388,17 +386,27 @@ void ath_beacon_tasklet(unsigned long data)
          * on the tsf to safeguard against missing an swba.
          */
 
-        intval = cur_conf->beacon_interval ? : ATH_DEFAULT_BINTVAL;
 
-        tsf = ath9k_hw_gettsf64(ah);
-        tsf += TU_TO_USEC(ah->config.sw_beacon_response_time);
-        tsftu = TSF_TO_TU((tsf * ATH_BCBUF) >>32, tsf * ATH_BCBUF);
-        slot = (tsftu % (intval * ATH_BCBUF)) / intval;
-        vif = sc->beacon.bslot[slot];
+        if (ah->opmode == NL80211_IFTYPE_AP) {
+                u16 intval;
+                u32 tsftu;
+                u64 tsf;
+
+                intval = cur_conf->beacon_interval ? : ATH_DEFAULT_BINTVAL;
+                tsf = ath9k_hw_gettsf64(ah);
+                tsf += TU_TO_USEC(ah->config.sw_beacon_response_time);
+                tsftu = TSF_TO_TU((tsf * ATH_BCBUF) >>32, tsf * ATH_BCBUF);
+                slot = (tsftu % (intval * ATH_BCBUF)) / intval;
+                vif = sc->beacon.bslot[slot];
+
+                ath_dbg(common, ATH_DBG_BEACON,
+                        "slot %d [tsf %llu tsftu %u intval %u] vif %p\n",
+                        slot, tsf, tsftu / ATH_BCBUF, intval, vif);
+        } else {
+                slot = 0;
+                vif = sc->beacon.bslot[slot];
+        }
 
-        ath_dbg(common, ATH_DBG_BEACON,
-                "slot %d [tsf %llu tsftu %u intval %u] vif %p\n",
-                slot, tsf, tsftu / ATH_BCBUF, intval, vif);
 
         bfaddr = 0;
         if (vif) {