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" : "  "));