mac80211: Send the management frame at requested rate

Whenever the scan request or tx_mgmt is requesting not to
use CCK rate for managemet frames through
NL80211_ATTR_TX_NO_CCK_RATE attribute, then mac80211 should
select appropriate least non-CCK rate. This could help to
send P2P probes and P2P action frames at non 11b rates
without diabling 11b rates globally.

Cc: Jouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c
index 3d5a2cb..f61244c 100644
--- a/net/mac80211/rate.c
+++ b/net/mac80211/rate.c
@@ -233,6 +233,27 @@
 	/* could not find a basic rate; use original selection */
 }
 
+static inline s8
+rate_lowest_non_cck_index(struct ieee80211_supported_band *sband,
+			  struct ieee80211_sta *sta)
+{
+	int i;
+
+	for (i = 0; i < sband->n_bitrates; i++) {
+		struct ieee80211_rate *srate = &sband->bitrates[i];
+		if ((srate->bitrate == 10) || (srate->bitrate == 20) ||
+		    (srate->bitrate == 55) || (srate->bitrate == 110))
+			continue;
+
+		if (rate_supported(sta, sband->band, i))
+			return i;
+	}
+
+	/* No matching rate found */
+	return 0;
+}
+
+
 bool rate_control_send_low(struct ieee80211_sta *sta,
 			   void *priv_sta,
 			   struct ieee80211_tx_rate_control *txrc)
@@ -242,7 +263,13 @@
 	int mcast_rate;
 
 	if (!sta || !priv_sta || rc_no_data_or_no_ack(txrc)) {
-		info->control.rates[0].idx = rate_lowest_index(txrc->sband, sta);
+		if ((sband->band != IEEE80211_BAND_2GHZ) ||
+		    !(info->flags & IEEE80211_TX_CTL_NO_CCK_RATE))
+			info->control.rates[0].idx =
+				rate_lowest_index(txrc->sband, sta);
+		else
+			info->control.rates[0].idx =
+				rate_lowest_non_cck_index(txrc->sband, sta);
 		info->control.rates[0].count =
 			(info->flags & IEEE80211_TX_CTL_NO_ACK) ?
 			1 : txrc->hw->max_rate_tries;