iwlwifi: fix in-column rate scaling

This patch fixes cases that the code raised or didn't decrease
the rate although the success ratio was not good.

Signed-off-by: Guy Cohen <guy.cohen@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 23 insertions, 22 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-4965-rs.c b/drivers/net/wireless/iwlwifi/iwl-4965-rs.c
index f28b3cc272df..a89639f958e1 100644
--- a/drivers/net/wireless/iwlwifi/iwl-4965-rs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-4965-rs.c
@@ -1336,7 +1336,7 @@ static int rs_move_legacy_other(struct iwl_priv *priv,
                                 lq_sta->search_better_tbl = 1;
                                 goto out;
                         }
-
+                        break;
                 case IWL_LEGACY_SWITCH_SISO:
                         IWL_DEBUG_RATE("LQ: Legacy switch to SISO\n");
 
@@ -1422,9 +1422,9 @@ static int rs_move_siso_to_other(struct iwl_priv *priv,
                                 lq_sta->search_better_tbl = 1;
                                 goto out;
                         }
-
+                        break;
                 case IWL_SISO_SWITCH_MIMO2:
-                        IWL_DEBUG_RATE("LQ: SISO switch to MIMO\n");
+                        IWL_DEBUG_RATE("LQ: SISO switch to MIMO2\n");
                         memcpy(search_tbl, tbl, sz);
                         search_tbl->is_SGI = 0;
                         search_tbl->ant_type = ANT_AB; /*FIXME:RS*/
@@ -1689,6 +1689,7 @@ static void rs_rate_scale_perform(struct iwl_priv *priv,
         u8 active_tbl = 0;
         u8 done_search = 0;
         u16 high_low;
+        s32 sr;
 #ifdef CONFIG_IWL4965_HT
         u8 tid = MAX_TID_COUNT;
 #endif
@@ -1864,6 +1865,8 @@ static void rs_rate_scale_perform(struct iwl_priv *priv,
         low = high_low & 0xff;
         high = (high_low >> 8) & 0xff;
 
+        sr = window->success_ratio;
+
         /* Collect measured throughputs for current and adjacent rates */
         current_tpt = window->average_tpt;
         if (low != IWL_RATE_INVALID)
@@ -1871,19 +1874,22 @@ static void rs_rate_scale_perform(struct iwl_priv *priv,
         if (high != IWL_RATE_INVALID)
                 high_tpt = tbl->win[high].average_tpt;
 
-        /* Assume rate increase */
-        scale_action = 1;
+        scale_action = 0;
 
         /* Too many failures, decrease rate */
-        if ((window->success_ratio <= IWL_RATE_DECREASE_TH) ||
-            (current_tpt == 0)) {
+        if ((sr <= IWL_RATE_DECREASE_TH) || (current_tpt == 0)) {
                 IWL_DEBUG_RATE("decrease rate because of low success_ratio\n");
                 scale_action = -1;
 
         /* No throughput measured yet for adjacent rates; try increase. */
         } else if ((low_tpt == IWL_INVALID_VALUE) &&
-                   (high_tpt == IWL_INVALID_VALUE))
-                scale_action = 1;
+                   (high_tpt == IWL_INVALID_VALUE)) {
+
+                if (high != IWL_RATE_INVALID && sr >= IWL_RATE_INCREASE_TH)
+                        scale_action = 1;
+                else if (low != IWL_RATE_INVALID)
+                        scale_action = -1;
+        }
 
         /* Both adjacent throughputs are measured, but neither one has better
          * throughput; we're using the best rate, don't change it! */
@@ -1899,9 +1905,10 @@ static void rs_rate_scale_perform(struct iwl_priv *priv,
                 /* Higher adjacent rate's throughput is measured */
                 if (high_tpt != IWL_INVALID_VALUE) {
                         /* Higher rate has better throughput */
-                        if (high_tpt > current_tpt)
+                        if (high_tpt > current_tpt &&
+                                        sr >= IWL_RATE_INCREASE_TH) {
                                 scale_action = 1;
-                        else {
+                        } else {
                                 IWL_DEBUG_RATE
                                     ("decrease rate because of high tpt\n");
                                 scale_action = -1;
@@ -1914,23 +1921,17 @@ static void rs_rate_scale_perform(struct iwl_priv *priv,
                                 IWL_DEBUG_RATE
                                     ("decrease rate because of low tpt\n");
                                 scale_action = -1;
-                        } else
+                        } else if (sr >= IWL_RATE_INCREASE_TH) {
                                 scale_action = 1;
+                        }
                 }
         }
 
         /* Sanity check; asked for decrease, but success rate or throughput
          * has been good at old rate.  Don't change it. */
-        if (scale_action == -1) {
-                if ((low != IWL_RATE_INVALID) &&
-                    ((window->success_ratio > IWL_RATE_HIGH_TH) ||
+        if ((scale_action == -1) && (low != IWL_RATE_INVALID) &&
+                    ((sr > IWL_RATE_HIGH_TH) ||
                      (current_tpt > (100 * tbl->expected_tpt[low]))))
-                        scale_action = 0;
-
-        /* Sanity check; asked for increase, but success rate has not been great
-         * even at old rate, higher rate will be worse.  Don't change it. */
-        } else if ((scale_action == 1) &&
-                   (window->success_ratio < IWL_RATE_INCREASE_TH))
                 scale_action = 0;
 
         switch (scale_action) {
@@ -1959,7 +1960,7 @@ static void rs_rate_scale_perform(struct iwl_priv *priv,
                     "high %d type %d\n",
                      index, scale_action, low, high, tbl->lq_type);
 
- lq_update:
+lq_update:
         /* Replace uCode's rate table for the destination station. */
         if (update_lq) {
                 rate = rate_n_flags_from_tbl(tbl, index, is_green);