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Date:      Tue, 19 Feb 2008 18:51:54 GMT
From:      Sam Leffler <sam@FreeBSD.org>
To:        Perforce Change Reviews <perforce@freebsd.org>
Subject:   PERFORCE change 135737 for review
Message-ID:  <200802191851.m1JIpsqZ087069@repoman.freebsd.org>
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http://perforce.freebsd.org/chv.cgi?CH=135737

Change 135737 by sam@sam_ebb on 2008/02/19 18:51:26

	fixup staggered beacon scheduling:
	o assign vap 0 to slot 0 always to optimize single bss operation
	o correct slot assignment spreading
	o switch stagbeacons on+off based on the number of vaps beaconing

Affected files ...

.. //depot/projects/vap/sys/dev/ath/if_ath.c#28 edit

Differences ...

==== //depot/projects/vap/sys/dev/ath/if_ath.c#28 (text+ko) ====

@@ -719,6 +719,28 @@
 	if (i != 0 || --sc->sc_nbssid0 == 0)
 		sc->sc_bssidmask &= ~(1<<i);
 }
+/*
+ * Assign a beacon xmit slot.  We try to space out
+ * assignments so when beacons are staggered the
+ * traffic coming out of the cab q has maximal time
+ * to go out before the next beacon is scheduled.
+ */
+static int
+assign_bslot(struct ath_softc *sc)
+{
+	u_int slot, free;
+
+	free = 0;
+	for (slot = 0; slot < ATH_BCBUF; slot++)
+		if (sc->sc_bslot[slot] == NULL) {
+			if (sc->sc_bslot[(slot+1)%ATH_BCBUF] == NULL &&
+			    sc->sc_bslot[(slot-1)%ATH_BCBUF] == NULL)
+				return slot;
+			free = slot;
+			/* NB: keep looking for a double slot */
+		}
+	return free;
+}
 
 static struct ieee80211vap *
 ath_vap_create(struct ieee80211com *ic,
@@ -796,6 +818,9 @@
 		device_printf(sc->sc_dev, "unknown opmode %d\n", opmode);
 		return NULL;
 	}
+	/*
+	 * Check that a beacon buffer is available; the code below assumes it.
+	 */
 	if (needbeacon & STAILQ_EMPTY(&sc->sc_bbuf)) {
 		device_printf(sc->sc_dev, "no beacon buffer available\n");
 		return NULL;
@@ -808,6 +833,7 @@
 		return NULL;
 	}
 
+	/* STA, AHDEMO? */
 	if (opmode == IEEE80211_M_HOSTAP)
 		assign_address(sc, mac, flags & IEEE80211_CLONE_BSSID);
 
@@ -841,34 +867,17 @@
 		avp->av_bcbuf = STAILQ_FIRST(&sc->sc_bbuf);
 		STAILQ_REMOVE_HEAD(&sc->sc_bbuf, bf_list);
 		if (opmode != IEEE80211_M_IBSS || !sc->sc_hasveol) {
-			int slot;
 			/*
 			 * Assign the vap to a beacon xmit slot.  As above
 			 * this cannot fail to find a free one.
 			 */
-			avp->av_bslot = 0;
-			for (slot = 0; slot < ATH_BCBUF; slot++) {
-				if (sc->sc_bslot[slot] == NULL) {
-					/*
-					 * XXX hack, space out slots to better
-					 * deal with traffic coming out of the
-					 * cab q.
-					 */
-					if (slot + 1 < ATH_BCBUF &&
-					    sc->sc_bslot[slot+1] == NULL) {
-						avp->av_bslot = slot + 1;
-						break;
-					} 
-					avp->av_bslot = slot;
-					/* NB: keep looking for a double slot */
-				}
-			}
+			avp->av_bslot = assign_bslot(sc);
 			KASSERT(sc->sc_bslot[avp->av_bslot] == NULL,
 			    ("beacon slot %u not empty", avp->av_bslot));
 			sc->sc_bslot[avp->av_bslot] = vap;
 			sc->sc_nbcnvaps++;
 		}
-		if (sc->sc_hastsfadd) {
+		if (sc->sc_hastsfadd && sc->sc_nbcnvaps > 0) {
 			/*
 			 * Multple vaps are to transmit beacons and we
 			 * have h/w support for TSF adjusting; enable
@@ -946,8 +955,11 @@
 		}
 		ath_beacon_return(sc, avp->av_bcbuf);
 		avp->av_bcbuf = NULL;
-		if (sc->sc_nbcnvaps == 0)
+		if (sc->sc_nbcnvaps == 0) {
 			sc->sc_stagbeacons = 0;
+			if (sc->sc_hastsfadd)
+				ath_hal_settsfadjust(sc->sc_ah, 0);
+		}
 		/*
 		 * Reclaim any pending mcast frames for the vap.
 		 */

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