3 files changed, 49 insertions, 36 deletions

diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c
index f8d99a54798f..1c36c9b4fa4a 100644
--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -69,14 +69,31 @@ rix_to_ndx(struct minstrel_sta_info *mi, int rix)
 	return i;
 }
 
+/* find & sort topmost throughput rates */
+static inline void
+minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list)
+{
+	int j = MAX_THR_RATES;
+
+	while (j > 0 && mi->r[i].cur_tp > mi->r[tp_list[j - 1]].cur_tp)
+		j--;
+	if (j < MAX_THR_RATES - 1)
+		memmove(&tp_list[j + 1], &tp_list[j], MAX_THR_RATES - (j + 1));
+	if (j < MAX_THR_RATES)
+		tp_list[j] = i;
+}
+
 static void
 minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
 {
-	u32 max_tp = 0, index_max_tp = 0, index_max_tp2 = 0;
-	u32 max_prob = 0, index_max_prob = 0;
+	u8 tmp_tp_rate[MAX_THR_RATES];
+	u8 tmp_prob_rate = 0;
 	u32 usecs;
 	int i;
 
+	for (i=0; i < MAX_THR_RATES; i++)
+	    tmp_tp_rate[i] = 0;
+
 	for (i = 0; i < mi->n_rates; i++) {
 		struct minstrel_rate *mr = &mi->r[i];
 
@@ -120,35 +137,27 @@ minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
 		}
 		if (!mr->adjusted_retry_count)
 			mr->adjusted_retry_count = 2;
-	}
 
-	for (i = 0; i < mi->n_rates; i++) {
-		struct minstrel_rate *mr = &mi->r[i];
-		if (max_tp < mr->cur_tp) {
-			index_max_tp = i;
-			max_tp = mr->cur_tp;
-		}
-		if (max_prob < mr->probability) {
-			index_max_prob = i;
-			max_prob = mr->probability;
+		minstrel_sort_best_tp_rates(mi, i, tmp_tp_rate);
+
+		/* To determine the most robust rate (max_prob_rate) used at
+		 * 3rd mmr stage we distinct between two cases:
+		 * (1) if any success probabilitiy >= 95%, out of those rates
+		 * choose the maximum throughput rate as max_prob_rate
+		 * (2) if all success probabilities < 95%, the rate with
+		 * highest success probability is choosen as max_prob_rate */
+		if (mr->probability >= MINSTREL_FRAC(95,100)) {
+			if (mr->cur_tp >= mi->r[tmp_prob_rate].cur_tp)
+				tmp_prob_rate = i;
+		} else {
+			if (mr->probability >= mi->r[tmp_prob_rate].probability)
+				tmp_prob_rate = i;
 		}
 	}
 
-	max_tp = 0;
-	for (i = 0; i < mi->n_rates; i++) {
-		struct minstrel_rate *mr = &mi->r[i];
-
-		if (i == index_max_tp)
-			continue;
-
-		if (max_tp < mr->cur_tp) {
-			index_max_tp2 = i;
-			max_tp = mr->cur_tp;
-		}
-	}
-	mi->max_tp_rate = index_max_tp;
-	mi->max_tp_rate2 = index_max_tp2;
-	mi->max_prob_rate = index_max_prob;
+	/* Assign the new rate set */
+	memcpy(mi->max_tp_rate, tmp_tp_rate, sizeof(mi->max_tp_rate));
+	mi->max_prob_rate = tmp_prob_rate;
 
 	/* Reset update timer */
 	mi->stats_update = jiffies;
@@ -254,7 +263,7 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
 		sampling_ratio = mp->lookaround_rate;
 
 	/* init rateindex [ndx] with max throughput rate */
-	ndx = mi->max_tp_rate;
+	ndx = mi->max_tp_rate[0];
 
 	/* increase sum packet counter */
 	mi->packet_count++;
@@ -322,7 +331,7 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
 	 * to use it, as this only wastes precious airtime */
 	if (!mrr_capable && rate_sampling &&
 	   (mi->r[ndx].probability > MINSTREL_FRAC(95, 100)))
-		ndx = mi->max_tp_rate;
+		ndx = mi->max_tp_rate[0];
 
 	/* mrr setup for 1st stage */
 	ar[0].idx = mi->r[ndx].rix;
@@ -342,9 +351,9 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
 		if (indirect_rate_sampling)
 			mrr_ndx[0] = sample_ndx;
 		else
-			mrr_ndx[0] = mi->max_tp_rate;
+			mrr_ndx[0] = mi->max_tp_rate[0];
 	} else {
-		mrr_ndx[0] = mi->max_tp_rate2;
+		mrr_ndx[0] = mi->max_tp_rate[1];
 	}
 
 	/* mrr setup for 3rd & 4th stage */
diff --git a/net/mac80211/rc80211_minstrel.h b/net/mac80211/rc80211_minstrel.h
index a0ccc5779910..85ebf42cb46d 100644
--- a/net/mac80211/rc80211_minstrel.h
+++ b/net/mac80211/rc80211_minstrel.h
@@ -18,6 +18,9 @@
 #define MINSTREL_FRAC(val, div) (((val) << MINSTREL_SCALE) / div)
 #define MINSTREL_TRUNC(val) ((val) >> MINSTREL_SCALE)
 
+/* number of highest throughput rates to consider*/
+#define MAX_THR_RATES 4
+
 /*
  * Perform EWMA (Exponentially Weighted Moving Average) calculation
   */
@@ -65,9 +68,8 @@ struct minstrel_sta_info {
 
 	unsigned int lowest_rix;
 
-	unsigned int max_tp_rate;
-	unsigned int max_tp_rate2;
-	unsigned int max_prob_rate;
+	u8 max_tp_rate[MAX_THR_RATES];
+	u8 max_prob_rate;
 	unsigned int packet_count;
 	unsigned int sample_count;
 	int sample_deferred;
diff --git a/net/mac80211/rc80211_minstrel_debugfs.c b/net/mac80211/rc80211_minstrel_debugfs.c
index c0ebfaca6ba0..d1048348d399 100644
--- a/net/mac80211/rc80211_minstrel_debugfs.c
+++ b/net/mac80211/rc80211_minstrel_debugfs.c
@@ -73,8 +73,10 @@ minstrel_stats_open(struct inode *inode, struct file *file)
 	for (i = 0; i < mi->n_rates; i++) {
 		struct minstrel_rate *mr = &mi->r[i];
 
-		*(p++) = (i == mi->max_tp_rate) ? 'T' : ' ';
-		*(p++) = (i == mi->max_tp_rate2) ? 't' : ' ';
+		*(p++) = (i == mi->max_tp_rate[0]) ? 'A' : ' ';
+		*(p++) = (i == mi->max_tp_rate[1]) ? 'B' : ' ';
+		*(p++) = (i == mi->max_tp_rate[2]) ? 'C' : ' ';
+		*(p++) = (i == mi->max_tp_rate[3]) ? 'D' : ' ';
 		*(p++) = (i == mi->max_prob_rate) ? 'P' : ' ';
 		p += sprintf(p, "%3u%s", mr->bitrate / 2,
 				(mr->bitrate & 1 ? ".5" : "  "));