iwlwifi: mvm: rs: fix success ratio comparison in rs_get_best_rate

success_ratio is actually 128 * SR in percentage while
IWL_MVM_RS_SR_NO_DECREASE is 85%. Fix this by using RS_PERCENT().
This bug caused the if branch to be always executed. This in turn
led to always selecting a rate, following a column switch, in which
the expected throughput would exceed the best expected current throughput.
In some scenarios where the success ratio isn't >85% such a rate
could be too aggressive leading us to avoid the new column.
This has the potential of causing sub optimal performance.

Reported-by: Moshe Harel <moshe.harel@intel.com>
Signed-off-by: Eyal Shapira <eyalx.shapira@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

diff --git a/drivers/net/wireless/iwlwifi/mvm/rs.c b/drivers/net/wireless/iwlwifi/mvm/rs.c
index 2bf2a08957234a42266e79cab9221532153953f7..435e1e40edb87e355f96778090a4aa79950b9603 100644 (file)
--- a/drivers/net/wireless/iwlwifi/mvm/rs.c
+++ b/drivers/net/wireless/iwlwifi/mvm/rs.c
@@ -1527,7 +1527,7 @@ static s32 rs_get_best_rate(struct iwl_mvm *mvm,
        u32 target_tpt;
        int rate_idx;
 
-       if (success_ratio > IWL_MVM_RS_SR_NO_DECREASE) {
+       if (success_ratio >= RS_PERCENT(IWL_MVM_RS_SR_NO_DECREASE)) {
                target_tpt = 100 * expected_current_tpt;
                IWL_DEBUG_RATE(mvm,
                               "SR %d high. Find rate exceeding EXPECTED_CURRENT %d\n",
@@ -1535,7 +1535,7 @@ static s32 rs_get_best_rate(struct iwl_mvm *mvm,
        } else {
                target_tpt = lq_sta->last_tpt;
                IWL_DEBUG_RATE(mvm,
-                              "SR %d not thag good. Find rate exceeding ACTUAL_TPT %d\n",
+                              "SR %d not that good. Find rate exceeding ACTUAL_TPT %d\n",
                               success_ratio, target_tpt);
        }