iwlwifi: HT performance improvement changes

During rate scaling, checking for 0 retry count before decrement
the count by 1, this can avoid the retry count to become 255 (0xff),
which will cause the rate to drop faster than what we expect during good
condition (receive 0 retry packet). also change the algorithm to make
the rate not drop faster than what we like.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
index a6f4c74ff2b4..0929f310b2d4 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
@@ -801,7 +801,10 @@ static void rs_tx_status(void *priv_r, struct ieee80211_supported_band *sband,
             !(info->flags & IEEE80211_TX_STAT_AMPDU))
                 return;
 
-        retries = info->status.rates[0].count - 1;
+        if (info->flags & IEEE80211_TX_STAT_AMPDU)
+                retries = 0;
+        else
+                retries = info->status.rates[0].count - 1;
 
         if (retries > 15)
                 retries = 15;
@@ -1897,7 +1900,7 @@ static void rs_rate_scale_perform(struct iwl_priv *priv,
                 if (high != IWL_RATE_INVALID && sr >= IWL_RATE_INCREASE_TH)
                         scale_action = 1;
                 else if (low != IWL_RATE_INVALID)
-                        scale_action = -1;
+                        scale_action = 0;
         }
 
         /* Both adjacent throughputs are measured, but neither one has better
@@ -1918,9 +1921,7 @@ static void rs_rate_scale_perform(struct iwl_priv *priv,
                                         sr >= IWL_RATE_INCREASE_TH) {
                                 scale_action = 1;
                         } else {
-                                IWL_DEBUG_RATE(priv,
-                                    "decrease rate because of high tpt\n");
-                                scale_action = -1;
+                                scale_action = 0;
                         }
 
                 /* Lower adjacent rate's throughput is measured */