From 267a90127472be70b02ab13cbd355b5013e2aa51 Mon Sep 17 00:00:00 2001 From: Jouni Malinen Date: Wed, 20 May 2009 21:56:39 +0300 Subject: [PATCH] ath9k: Optimize TBTT/DTIM calculation for timers The previous version used a simple loop to go through all Beacon frames when determining the next TBTT and DTIM count. This is not too bad for the case where the setup happens before timesync (i.e., very small TSF), but this can become very heavy operation if a short Beacon interval is used and the current TSF is large. In preparation for a patch to update timer setup based on Beacon timestamp, optimize this routine to take fixed time regardless of the actual TSF value. Signed-off-by: Jouni Malinen Signed-off-by: John W. Linville --- drivers/net/wireless/ath/ath9k/beacon.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) diff --git a/drivers/net/wireless/ath/ath9k/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c index 57f91a9..a21b213 100644 --- a/drivers/net/wireless/ath/ath9k/beacon.c +++ b/drivers/net/wireless/ath/ath9k/beacon.c @@ -559,6 +559,7 @@ static void ath_beacon_config_sta(struct ath_softc *sc, int cfpperiod, cfpcount; u32 nexttbtt = 0, intval, tsftu; u64 tsf; + int num_beacons, offset, dtim_dec_count, cfp_dec_count; memset(&bs, 0, sizeof(bs)); intval = conf->beacon_interval & ATH9K_BEACON_PERIOD; @@ -586,14 +587,27 @@ static void ath_beacon_config_sta(struct ath_softc *sc, */ tsf = ath9k_hw_gettsf64(sc->sc_ah); tsftu = TSF_TO_TU(tsf>>32, tsf) + FUDGE; - do { + + num_beacons = tsftu / intval + 1; + offset = tsftu % intval; + nexttbtt = tsftu - offset; + if (offset) nexttbtt += intval; - if (--dtimcount < 0) { - dtimcount = dtimperiod - 1; - if (--cfpcount < 0) - cfpcount = cfpperiod - 1; - } - } while (nexttbtt < tsftu); + + /* DTIM Beacon every dtimperiod Beacon */ + dtim_dec_count = num_beacons % dtimperiod; + /* CFP every cfpperiod DTIM Beacon */ + cfp_dec_count = (num_beacons / dtimperiod) % cfpperiod; + if (dtim_dec_count) + cfp_dec_count++; + + dtimcount -= dtim_dec_count; + if (dtimcount < 0) + dtimcount += dtimperiod; + + cfpcount -= cfp_dec_count; + if (cfpcount < 0) + cfpcount += cfpperiod; bs.bs_intval = intval; bs.bs_nexttbtt = nexttbtt; -- 2.7.4