svn commit: r222683 - head/sys/net80211

[Bernhard Schmidt]

Author: bschmidt
Date: Sat Jun  4 15:05:32 2011
New Revision: 222683
URL: http://svn.freebsd.org/changeset/base/222683

Log:
  Certain adapters have HT40 support on some but not all channels. The
  Intel 4965 devices for example have HT40 on 2GHz completely disabled
  but it is still supported for 5GHz. To handle that in sta mode we
  need to check if we can "upgrade" to a HT40 channel after the
  association, if that is not possible but we are still announcing
  support to the remote side we are left with a very flabby connection.
  
  Reviewed by:	adrian

Modified:
  head/sys/net80211/ieee80211_ht.c

Modified: head/sys/net80211/ieee80211_ht.c
==============================================================================
--- head/sys/net80211/ieee80211_ht.c	Sat Jun  4 14:28:09 2011	(r222682)
+++ head/sys/net80211/ieee80211_ht.c	Sat Jun  4 15:05:32 2011	(r222683)
@@ -2520,6 +2520,7 @@ ieee80211_add_htcap_body(uint8_t *frm, s
 	frm[1] = (v) >> 8;			\
 	frm += 2;				\
 } while (0)
+	struct ieee80211com *ic = ni->ni_ic;
 	struct ieee80211vap *vap = ni->ni_vap;
 	uint16_t caps, extcaps;
 	int rxmax, density;
@@ -2543,6 +2544,17 @@ ieee80211_add_htcap_body(uint8_t *frm, s
 		/* use advertised setting (XXX locally constraint) */
 		rxmax = MS(ni->ni_htparam, IEEE80211_HTCAP_MAXRXAMPDU);
 		density = MS(ni->ni_htparam, IEEE80211_HTCAP_MPDUDENSITY);
+
+		/*
+		 * NB: Hardware might support HT40 on some but not all
+		 * channels. We can't determine this earlier because only
+		 * after association the channel is upgraded to HT based
+		 * on the negotiated capabilities.
+		 */
+		if (ni->ni_chan != IEEE80211_CHAN_ANYC &&
+		    findhtchan(ic, ni->ni_chan, IEEE80211_CHAN_HT40U) == NULL &&
+		    findhtchan(ic, ni->ni_chan, IEEE80211_CHAN_HT40D) == NULL)
+			caps &= ~IEEE80211_HTCAP_CHWIDTH40;
 	} else {
 		/* override 20/40 use based on current channel */
 		if (IEEE80211_IS_CHAN_HT40(ni->ni_chan))