svn commit: r257881 - head/sys/net80211

[Adrian Chadd]

Author: adrian
Date: Sat Nov  9 07:30:13 2013
New Revision: 257881
URL: http://svnweb.freebsd.org/changeset/base/257881

Log:
  Fix AMRR to correctly select the initial rate.
  
  There were two bugs:
  
  * If the initial lowest rate didn't go through the loop at least once,
    the AMRR rate index would be the highest rate in the table
    (eg the rix mapping to MCS15) but rate would stay at the default
    value, namely 0.
  
    This meant that the initial rate selection would be MCS15 _but_ the
    node ni_txrate value would be MCS0.
  
  * If the node is 11n, then break out of the loop correctly.  Beforehand,
    my initial 11n AMRR commit would immediately exit out as it would
    fail the 11n check, then it would always fall through to the non-11n
    rate which would then see if it was < 36mbit (ie, "72"), which would
    always match.  Hence, it'd always return MCS15.
  
  Tested:
  
  * Intel Centrino 2230 STA (local changes), STA mode
  * Intel Wifi 5100, STA

Modified:
  head/sys/net80211/ieee80211_amrr.c

Modified: head/sys/net80211/ieee80211_amrr.c
==============================================================================
--- head/sys/net80211/ieee80211_amrr.c	Sat Nov  9 06:30:09 2013	(r257880)
+++ head/sys/net80211/ieee80211_amrr.c	Sat Nov  9 07:30:13 2013	(r257881)
@@ -199,13 +199,13 @@ amrr_node_init(struct ieee80211_node *ni
 	    amn->amn_rix--) {
 		/* legacy - anything < 36mbit, stop searching */
 		/* 11n - stop at MCS4 / MCS12 / MCS28 */
-		if (amrr_node_is_11n(ni) &&
-		    (rs->rs_rates[amn->amn_rix] & 0x7) < 4)
+		if (amrr_node_is_11n(ni)) {
+			if ((rs->rs_rates[amn->amn_rix] & 0x7) < 4)
+				break;
+		} else if ((rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL) <= 72)
 			break;
-		else if ((rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL) <= 72)
-			break;
-		rate = rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL;
 	}
+	rate = rs->rs_rates[amn->amn_rix] & IEEE80211_RATE_VAL;
 
 	/* if the rate is an 11n rate, ensure the MCS bit is set */
 	if (amrr_node_is_11n(ni))