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Date:      Tue, 22 Feb 2011 00:37:53 +0000 (UTC)
From:      Adrian Chadd <adrian@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r218932 - head/sys/dev/ath
Message-ID:  <201102220037.p1M0brv3088271@svn.freebsd.org>
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Author: adrian
Date: Tue Feb 22 00:37:53 2011
New Revision: 218932
URL: http://svn.freebsd.org/changeset/base/218932

Log:
  Shuffle around the RTS/CTS rate/duration logic.
  
  * Turn ath_tx_calc_ctsduration() into a function that
    returns the ctsduration, or -1 for HT rates;
  * add a printf() to ath_tx_calc_ctsduration() which will be
    very loud if somehow that function is called with an MCS
    rate;
  * Add ath_tx_get_rtscts_rate() which returns the RTS/CTS
    rate to use for the given data rate, incl. the short
    preamble flag;
  * Only call ath_tx_calc_ctsduration() for non-11n chipsets;
    11n chipsets don't require the rtscts duration to be
    calculated.

Modified:
  head/sys/dev/ath/if_ath_tx.c

Modified: head/sys/dev/ath/if_ath_tx.c
==============================================================================
--- head/sys/dev/ath/if_ath_tx.c	Tue Feb 22 00:01:19 2011	(r218931)
+++ head/sys/dev/ath/if_ath_tx.c	Tue Feb 22 00:37:53 2011	(r218932)
@@ -420,11 +420,12 @@ ath_tx_tag_crypto(struct ath_softc *sc, 
 	return 1;
 }
 
-static void
-ath_tx_calc_ctsduration(struct ath_hal *ah, int rix, int cix,
-    int shortPreamble, int pktlen, const HAL_RATE_TABLE *rt,
-    int flags, u_int8_t *ctsrate, int *ctsduration)
+static uint8_t
+ath_tx_get_rtscts_rate(struct ath_hal *ah, const HAL_RATE_TABLE *rt,
+    int rix, int cix, int shortPreamble)
 {
+	uint8_t ctsrate;
+
 	/*
 	 * CTS transmit rate is derived from the transmit rate
 	 * by looking in the h/w rate table.  We must also factor
@@ -432,7 +433,33 @@ ath_tx_calc_ctsduration(struct ath_hal *
 	 */
 	/* NB: cix is set above where RTS/CTS is enabled */
 	KASSERT(cix != 0xff, ("cix not setup"));
-	(*ctsrate) = rt->info[cix].rateCode;
+	ctsrate = rt->info[cix].rateCode;
+
+	/* XXX this should only matter for legacy rates */
+	if (shortPreamble)
+		ctsrate |= rt->info[cix].shortPreamble;
+
+	return ctsrate;
+}
+
+
+/*
+ * Calculate the RTS/CTS duration for legacy frames.
+ */
+static int
+ath_tx_calc_ctsduration(struct ath_hal *ah, int rix, int cix,
+    int shortPreamble, int pktlen, const HAL_RATE_TABLE *rt,
+    int flags)
+{
+	int ctsduration = 0;
+
+	/* This mustn't be called for HT modes */
+	if (rt->info[cix].phy == IEEE80211_T_HT) {
+		printf("%s: HT rate where it shouldn't be (0x%x)\n",
+		    __func__, rt->info[cix].rateCode);
+		return -1;
+	}
+
 	/*
 	 * Compute the transmit duration based on the frame
 	 * size and the size of an ACK frame.  We call into the
@@ -443,21 +470,22 @@ ath_tx_calc_ctsduration(struct ath_hal *
 	 *     use the precalculated ACK durations.
 	 */
 	if (shortPreamble) {
-		(*ctsrate) |= rt->info[cix].shortPreamble;
 		if (flags & HAL_TXDESC_RTSENA)		/* SIFS + CTS */
-			(*ctsduration) += rt->info[cix].spAckDuration;
-		(*ctsduration) += ath_hal_computetxtime(ah,
+			ctsduration += rt->info[cix].spAckDuration;
+		ctsduration += ath_hal_computetxtime(ah,
 			rt, pktlen, rix, AH_TRUE);
 		if ((flags & HAL_TXDESC_NOACK) == 0)	/* SIFS + ACK */
-			(*ctsduration) += rt->info[rix].spAckDuration;
+			ctsduration += rt->info[rix].spAckDuration;
 	} else {
 		if (flags & HAL_TXDESC_RTSENA)		/* SIFS + CTS */
-			(*ctsduration) += rt->info[cix].lpAckDuration;
-		(*ctsduration) += ath_hal_computetxtime(ah,
+			ctsduration += rt->info[cix].lpAckDuration;
+		ctsduration += ath_hal_computetxtime(ah,
 			rt, pktlen, rix, AH_FALSE);
 		if ((flags & HAL_TXDESC_NOACK) == 0)	/* SIFS + ACK */
-			(*ctsduration) += rt->info[rix].lpAckDuration;
+			ctsduration += rt->info[rix].lpAckDuration;
 	}
+
+	return ctsduration;
 }
 
 int
@@ -714,8 +742,12 @@ ath_tx_start(struct ath_softc *sc, struc
 	 */
 	ctsduration = 0;
 	if (flags & (HAL_TXDESC_RTSENA|HAL_TXDESC_CTSENA)) {
-		(void) ath_tx_calc_ctsduration(ah, rix, cix, shortPreamble, pktlen,
-		    rt, flags, &ctsrate, &ctsduration);
+		ctsrate = ath_tx_get_rtscts_rate(ah, rt, rix, cix, shortPreamble);
+
+		/* The 11n chipsets do ctsduration calculations for you */
+		if (! ath_tx_is_11n(sc))
+			ctsduration = ath_tx_calc_ctsduration(ah, rix, cix, shortPreamble,
+			    pktlen, rt, flags);
 		/*
 		 * Must disable multi-rate retry when using RTS/CTS.
 		 */
@@ -893,9 +925,12 @@ ath_tx_raw_start(struct ath_softc *sc, s
 	ctsduration = 0;
 	if (flags & (HAL_TXDESC_RTSENA|HAL_TXDESC_CTSENA)) {
 		cix = ath_tx_findrix(sc, params->ibp_ctsrate);
-		(void) ath_tx_calc_ctsduration(ah, rix, cix,
-		    params->ibp_flags & IEEE80211_BPF_SHORTPRE, pktlen,
-		    rt, flags, &ctsrate, &ctsduration);
+		ctsrate = ath_tx_get_rtscts_rate(ah, rt, rix, cix, params->ibp_flags & IEEE80211_BPF_SHORTPRE);
+		/* The 11n chipsets do ctsduration calculations for you */
+		if (! ath_tx_is_11n(sc))
+			ctsduration = ath_tx_calc_ctsduration(ah, rix, cix,
+			    params->ibp_flags & IEEE80211_BPF_SHORTPRE, pktlen,
+			    rt, flags);
 		/*
 		 * Must disable multi-rate retry when using RTS/CTS.
 		 */

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