update ath5k_beacon_update_timers() for better beacon timer calculation in a
variety of situations. most important is the possibility to call it with the
timestamp of a received beacon, when we detected that a HW merge has happened
and we need to reconfigure the beacon timers based on that.
we call this from the mac80211 callback reset_tsf now instead of beacon_update,
and there will be more use of it in the next patch.
drivers/net/wireless/ath5k/base.c: Changes-licensed-under: 3-Clause-BSD
Signed-off-by: Bruno Randolf <bruno@xxxxxxxxxxxxx>
---
drivers/net/wireless/ath5k/base.c | 109 +++++++++++++++++++++++++++++++------
1 files changed, 92 insertions(+), 17 deletions(-)
diff --git a/drivers/net/wireless/ath5k/base.c b/drivers/net/wireless/ath5k/base.c
index 784b359..ae3d470 100644
--- a/drivers/net/wireless/ath5k/base.c
+++ b/drivers/net/wireless/ath5k/base.c
@@ -290,6 +290,7 @@ static int ath5k_beacon_setup(struct ath5k_softc *sc,
struct ieee80211_tx_control *ctl);
static void ath5k_beacon_send(struct ath5k_softc *sc);
static void ath5k_beacon_config(struct ath5k_softc *sc);
+static void ath5k_beacon_update_timers(struct ath5k_softc *sc, u64 bc_tsf);
static inline u64 ath5k_extend_tsf(struct ath5k_hw *ah, u32 rstamp)
{
@@ -1980,34 +1981,102 @@ ath5k_beacon_send(struct ath5k_softc *sc)
}
+/**
+ * ath5k_beacon_update_timers - update beacon timers
+ *
+ * @sc: struct ath5k_softc pointer we are operating on
+ * @bc_tsf: the timestamp of the beacon. 0 to reset the TSF. -1 to perform a
+ * beacon timer update based on the current HW TSF.
+ *
+ * Calculate the next target beacon transmit time (TBTT) based on the timestamp
+ * of a received beacon or the current local hardware TSF and write it to the
+ * beacon timer registers.
+ *
+ * This is called in a variety of situations, e.g. when a beacon is received,
+ * when a HW merge has been detected, but also when an new IBSS is created or
+ * when we otherwise know we have to update the timers, but we keep it in this
+ * function to have it all together in one place.
+ */
static void
-ath5k_beacon_update_timers(struct ath5k_softc *sc)
+ath5k_beacon_update_timers(struct ath5k_softc *sc, u64 bc_tsf)
{
struct ath5k_hw *ah = sc->ah;
- u32 uninitialized_var(nexttbtt), intval, tsftu;
- u64 tsf;
+ u32 nexttbtt, intval, hw_tu, bc_tu;
+ u64 hw_tsf;
intval = sc->bintval & AR5K_BEACON_PERIOD;
if (WARN_ON(!intval))
return;
- /* current TSF converted to TU */
- tsf = ath5k_hw_get_tsf64(ah);
- tsftu = TSF_TO_TU(tsf);
+ /* beacon TSF converted to TU */
+ bc_tu = TSF_TO_TU(bc_tsf);
- /*
- * Pull nexttbtt forward to reflect the current
- * TSF. Add one intval otherwise the timespan
- * can be too short for ibss merges.
- */
- nexttbtt = tsftu + 2 * intval;
+ /* current TSF converted to TU */
+ hw_tsf = ath5k_hw_get_tsf64(ah);
+ hw_tu = TSF_TO_TU(hw_tsf);
- ATH5K_DBG(sc, ATH5K_DEBUG_BEACON,
- "hw tsftu %u nexttbtt %u intval %u\n", tsftu, nexttbtt, intval);
+#define FUDGE 3
+ /* we use FUDGE to make sure the next TBTT is ahead of the current TU */
+ if (bc_tsf == -1) {
+ /*
+ * no beacons received, called internally.
+ * just need to refresh timers based on HW TSF.
+ */
+ nexttbtt = roundup(hw_tu + FUDGE, intval);
+ } else if (bc_tsf == 0) {
+ /*
+ * no beacon received, probably called by ath5k_reset_tsf().
+ * reset TSF to start with 0.
+ */
+ nexttbtt = intval;
+ intval |= AR5K_BEACON_RESET_TSF;
+ } else if (bc_tsf > hw_tsf) {
+ /*
+ * beacon received, SW merge happend but HW TSF not yet updated.
+ * not possible to reconfigure timers yet, but next time we
+ * receive a beacon with the same BSSID, the hardware will
+ * automatically update the TSF and then we need to reconfigure
+ * the timers.
+ */
+ ATH5K_DBG_UNLIMIT(sc, ATH5K_DEBUG_BEACON,
+ "need to wait for HW TSF sync\n");
+ return;
+ } else {
+ /*
+ * most important case for beacon synchronization between STA.
+ *
+ * beacon received and HW TSF has been already updated by HW.
+ * update next TBTT based on the TSF of the beacon, but make
+ * sure it is ahead of our local TSF timer.
+ */
+ nexttbtt = bc_tu + roundup(hw_tu + FUDGE - bc_tu, intval);
+ }
+#undef FUDGE
intval |= AR5K_BEACON_ENA;
-
ath5k_hw_init_beacon(ah, nexttbtt, intval);
+
+ /*
+ * debugging output last in order to preserve the time critical aspect
+ * of this function
+ */
+ if (bc_tsf == -1)
+ ATH5K_DBG_UNLIMIT(sc, ATH5K_DEBUG_BEACON,
+ "reconfigured timers based on HW TSF\n");
+ else if (bc_tsf == 0)
+ ATH5K_DBG_UNLIMIT(sc, ATH5K_DEBUG_BEACON,
+ "reset HW TSF and timers\n");
+ else
+ ATH5K_DBG_UNLIMIT(sc, ATH5K_DEBUG_BEACON,
+ "updated timers based on beacon TSF\n");
+
+ ATH5K_DBG_UNLIMIT(sc, ATH5K_DEBUG_BEACON,
+ "bc_tsf %llx hw_tsf %llx bc_tu %u hw_tu %u nexttbtt %u\n",
+ bc_tsf, hw_tsf, bc_tu, hw_tu, nexttbtt);
+ ATH5K_DBG_UNLIMIT(sc, ATH5K_DEBUG_BEACON, "intval %u %s %s\n",
+ intval & AR5K_BEACON_PERIOD,
+ intval & AR5K_BEACON_ENA ? "AR5K_BEACON_ENA" : "",
+ intval & AR5K_BEACON_RESET_TSF ? "AR5K_BEACON_RESET_TSF" : "");
}
@@ -2041,7 +2110,6 @@ ath5k_beacon_config(struct ath5k_softc *sc)
* only once here.
*/
ath5k_beaconq_config(sc);
- ath5k_beacon_update_timers(sc);
if (!ath5k_hw_hasveol(ah))
sc->imask |= AR5K_INT_SWBA;
@@ -2791,7 +2859,14 @@ ath5k_reset_tsf(struct ieee80211_hw *hw)
{
struct ath5k_softc *sc = hw->priv;
- ath5k_hw_reset_tsf(sc->ah);
+ /*
+ * in IBSS mode we need to update the beacon timers too.
+ * this will also reset the TSF if we call it with 0
+ */
+ if (sc->opmode == IEEE80211_IF_TYPE_IBSS)
+ ath5k_beacon_update_timers(sc, 0);
+ else
+ ath5k_hw_reset_tsf(sc->ah);
}
static int
-
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