iwlwifi: clean up rs_tx_status

Cut down on redundant code, reorganize structure, and add/improve comments.
Should contain no functional changes.

Signed-off-by: Daniel C Halperin <daniel.c.halperin@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 108 insertions, 122 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
index 469d56321d8..cd24763d5fd 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
@@ -821,27 +821,45 @@ out:
 }
 
 /*
+ * Simple function to compare two rate scale table types
+ */
+static bool table_type_matches(struct iwl_scale_tbl_info *a,
+                               struct iwl_scale_tbl_info *b)
+{
+        return (a->lq_type == b->lq_type) && (a->ant_type == b->ant_type) &&
+                (a->is_SGI == b->is_SGI);
+}
+/*
+ * Static function to get the expected throughput from an iwl_scale_tbl_info
+ * that wraps a NULL pointer check
+ */
+static s32 get_expected_tpt(struct iwl_scale_tbl_info *tbl, int rs_index)
+{
+        if (tbl->expected_tpt)
+                return tbl->expected_tpt[rs_index];
+        return 0;
+}
+
+/*
  * mac80211 sends us Tx status
  */
 static void rs_tx_status(void *priv_r, struct ieee80211_supported_band *sband,
                          struct ieee80211_sta *sta, void *priv_sta,
                          struct sk_buff *skb)
 {
-        int status;
-        u8 retries;
-        int rs_index, mac_index, index = 0;
+        int legacy_success;
+        int retries;
+        int rs_index, mac_index, i;
         struct iwl_lq_sta *lq_sta = priv_sta;
         struct iwl_link_quality_cmd *table;
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
         struct iwl_priv *priv = (struct iwl_priv *)priv_r;
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
         struct iwl_rate_scale_data *window = NULL;
-        struct iwl_rate_scale_data *search_win = NULL;
         enum mac80211_rate_control_flags mac_flags;
         u32 tx_rate;
         struct iwl_scale_tbl_info tbl_type;
-        struct iwl_scale_tbl_info *curr_tbl, *search_tbl;
-        u8 active_index = 0;
+        struct iwl_scale_tbl_info *curr_tbl, *other_tbl;
         s32 tpt = 0;
 
         IWL_DEBUG_RATE_LIMIT(priv, "get frame ack response, update rate scale window\n");
@@ -855,25 +873,10 @@ static void rs_tx_status(void *priv_r, struct ieee80211_supported_band *sband,
             !(info->flags & IEEE80211_TX_STAT_AMPDU))
                 return;
 
-        if (info->flags & IEEE80211_TX_STAT_AMPDU)
-                retries = 0;
-        else
-                retries = info->status.rates[0].count - 1;
-
-        if (retries > 15)
-                retries = 15;
 
         if ((priv->iw_mode == NL80211_IFTYPE_ADHOC) &&
             !lq_sta->ibss_sta_added)
-                goto out;
-
-        table = &lq_sta->lq;
-        active_index = lq_sta->active_tbl;
-
-        curr_tbl = &(lq_sta->lq_info[active_index]);
-        search_tbl = &(lq_sta->lq_info[(1 - active_index)]);
-        window = (struct iwl_rate_scale_data *)&(curr_tbl->win[0]);
-        search_win = (struct iwl_rate_scale_data *)&(search_tbl->win[0]);
+                return;
 
         /*
          * Ignore this Tx frame response if its initial rate doesn't match
@@ -883,6 +886,7 @@ static void rs_tx_status(void *priv_r, struct ieee80211_supported_band *sband,
          * to check "search" mode, or a prior "search" mode after we've moved
          * to a new "search" mode (which might become the new "active" mode).
          */
+        table = &lq_sta->lq;
         tx_rate = le32_to_cpu(table->rs_table[0].rate_n_flags);
         rs_get_tbl_info_from_mcs(tx_rate, priv->band, &tbl_type, &rs_index);
         if (priv->band == IEEE80211_BAND_5GHZ)
@@ -901,7 +905,7 @@ static void rs_tx_status(void *priv_r, struct ieee80211_supported_band *sband,
                 if (priv->band == IEEE80211_BAND_2GHZ)
                         mac_index += IWL_FIRST_OFDM_RATE;
         }
-
+        /* Here we actually compare this rate to the latest LQ command */
         if ((mac_index < 0) ||
             (tbl_type.is_SGI != !!(mac_flags & IEEE80211_TX_RC_SHORT_GI)) ||
             (tbl_type.is_ht40 != !!(mac_flags & IEEE80211_TX_RC_40_MHZ_WIDTH)) ||
@@ -911,124 +915,106 @@ static void rs_tx_status(void *priv_r, struct ieee80211_supported_band *sband,
             (!!(tx_rate & RATE_MCS_GF_MSK) != !!(mac_flags & IEEE80211_TX_RC_GREEN_FIELD)) ||
             (rs_index != mac_index)) {
                 IWL_DEBUG_RATE(priv, "initial rate %d does not match %d (0x%x)\n", mac_index, rs_index, tx_rate);
-                /* the last LQ command could failed so the LQ in ucode not
-                 * the same in driver sync up
+                /*
+                 * Since rates mis-match, the last LQ command may have failed.
+                 * After IWL_MISSED_RATE_MAX mis-matches, resync the uCode with
+                 * ... driver.
                  */
                 lq_sta->missed_rate_counter++;
                 if (lq_sta->missed_rate_counter > IWL_MISSED_RATE_MAX) {
                         lq_sta->missed_rate_counter = 0;
                         iwl_send_lq_cmd(priv, &lq_sta->lq, CMD_ASYNC);
                 }
-                goto out;
+                /* Regardless, ignore this status info for outdated rate */
+                return;
+        } else
+                /* Rate did match, so reset the missed_rate_counter */
+                lq_sta->missed_rate_counter = 0;
+
+        /* Figure out if rate scale algorithm is in active or search table */
+        if (table_type_matches(&tbl_type,
+                                &(lq_sta->lq_info[lq_sta->active_tbl]))) {
+                curr_tbl = &(lq_sta->lq_info[lq_sta->active_tbl]);
+                other_tbl = &(lq_sta->lq_info[1 - lq_sta->active_tbl]);
+        } else if (table_type_matches(&tbl_type,
+                                &lq_sta->lq_info[1 - lq_sta->active_tbl])) {
+                curr_tbl = &(lq_sta->lq_info[1 - lq_sta->active_tbl]);
+                other_tbl = &(lq_sta->lq_info[lq_sta->active_tbl]);
+        } else {
+                IWL_DEBUG_RATE(priv, "Neither active nor search matches tx rate\n");
+                return;
         }
+        window = (struct iwl_rate_scale_data *)&(curr_tbl->win[0]);
 
-        lq_sta->missed_rate_counter = 0;
-        /* Update frame history window with "failure" for each Tx retry. */
-        while (retries) {
-                /* Look up the rate and other info used for each tx attempt.
-                 * Each tx attempt steps one entry deeper in the rate table. */
-                tx_rate = le32_to_cpu(table->rs_table[index].rate_n_flags);
-                rs_get_tbl_info_from_mcs(tx_rate, priv->band,
-                                          &tbl_type, &rs_index);
-
-                /* If type matches "search" table,
-                 * add failure to "search" history */
-                if ((tbl_type.lq_type == search_tbl->lq_type) &&
-                    (tbl_type.ant_type == search_tbl->ant_type) &&
-                    (tbl_type.is_SGI == search_tbl->is_SGI)) {
-                        if (search_tbl->expected_tpt)
-                                tpt = search_tbl->expected_tpt[rs_index];
-                        else
-                                tpt = 0;
-                        rs_collect_tx_data(search_win, rs_index, tpt, 1, 0);
-
-                /* Else if type matches "current/active" table,
-                 * add failure to "current/active" history */
-                } else if ((tbl_type.lq_type == curr_tbl->lq_type) &&
-                           (tbl_type.ant_type == curr_tbl->ant_type) &&
-                           (tbl_type.is_SGI == curr_tbl->is_SGI)) {
-                        if (curr_tbl->expected_tpt)
-                                tpt = curr_tbl->expected_tpt[rs_index];
-                        else
-                                tpt = 0;
-                        rs_collect_tx_data(window, rs_index, tpt, 1, 0);
+        /*
+         * Updating the frame history depends on whether packets were
+         * aggregated.
+         *
+         * For aggregation, all packets were transmitted at the same rate, the
+         * first index into rate scale table.
+         */
+        if (info->flags & IEEE80211_TX_STAT_AMPDU) {
+                tx_rate = le32_to_cpu(table->rs_table[0].rate_n_flags);
+                rs_get_tbl_info_from_mcs(tx_rate, priv->band, &tbl_type,
+                                &rs_index);
+                tpt = get_expected_tpt(curr_tbl, rs_index);
+                rs_collect_tx_data(window, rs_index, tpt,
+                                   info->status.ampdu_ack_len,
+                                   info->status.ampdu_ack_map);
+
+                /* Update success/fail counts if not searching for new mode */
+                if (lq_sta->stay_in_tbl) {
+                        lq_sta->total_success += info->status.ampdu_ack_map;
+                        lq_sta->total_failed += (info->status.ampdu_ack_len -
+                                        info->status.ampdu_ack_map);
                 }
-
-                /* If not searching for a new mode, increment failed counter
-                 * ... this helps determine when to start searching again */
-                if (lq_sta->stay_in_tbl)
-                        lq_sta->total_failed++;
-                --retries;
-                index++;
-
-        }
-
+        } else {
         /*
-         * Find (by rate) the history window to update with final Tx attempt;
-         * if Tx was successful first try, use original rate,
-         * else look up the rate that was, finally, successful.
+         * For legacy, update frame history with for each Tx retry.
          */
-        tx_rate = le32_to_cpu(table->rs_table[index].rate_n_flags);
-        lq_sta->last_rate_n_flags = tx_rate;
-        rs_get_tbl_info_from_mcs(tx_rate, priv->band, &tbl_type, &rs_index);
-
-        /* Update frame history window with "success" if Tx got ACKed ... */
-        status = !!(info->flags & IEEE80211_TX_STAT_ACK);
-
-        /* If type matches "search" table,
-         * add final tx status to "search" history */
-        if ((tbl_type.lq_type == search_tbl->lq_type) &&
-            (tbl_type.ant_type == search_tbl->ant_type) &&
-            (tbl_type.is_SGI == search_tbl->is_SGI)) {
-                if (search_tbl->expected_tpt)
-                        tpt = search_tbl->expected_tpt[rs_index];
-                else
-                        tpt = 0;
-                if (info->flags & IEEE80211_TX_STAT_AMPDU)
-                        rs_collect_tx_data(search_win, rs_index, tpt,
-                                           info->status.ampdu_ack_len,
-                                           info->status.ampdu_ack_map);
-                else
-                        rs_collect_tx_data(search_win, rs_index, tpt,
-                                           1, status);
-        /* Else if type matches "current/active" table,
-         * add final tx status to "current/active" history */
-        } else if ((tbl_type.lq_type == curr_tbl->lq_type) &&
-                   (tbl_type.ant_type == curr_tbl->ant_type) &&
-                   (tbl_type.is_SGI == curr_tbl->is_SGI)) {
-                if (curr_tbl->expected_tpt)
-                        tpt = curr_tbl->expected_tpt[rs_index];
-                else
-                        tpt = 0;
-                if (info->flags & IEEE80211_TX_STAT_AMPDU)
-                        rs_collect_tx_data(window, rs_index, tpt,
-                                           info->status.ampdu_ack_len,
-                                           info->status.ampdu_ack_map);
-                else
-                        rs_collect_tx_data(window, rs_index, tpt,
-                                           1, status);
-        }
+                retries = info->status.rates[0].count - 1;
+                /* HW doesn't send more than 15 retries */
+                retries = min(retries, 15);
+
+                /* The last transmission may have been successful */
+                legacy_success = !!(info->flags & IEEE80211_TX_STAT_ACK);
+                /* Collect data for each rate used during failed TX attempts */
+                for (i = 0; i <= retries; ++i) {
+                        tx_rate = le32_to_cpu(table->rs_table[i].rate_n_flags);
+                        rs_get_tbl_info_from_mcs(tx_rate, priv->band,
+                                        &tbl_type, &rs_index);
+                        /*
+                         * Only collect stats if retried rate is in the same RS
+                         * table as active/search.
+                         */
+                        if (table_type_matches(&tbl_type, curr_tbl))
+                                tpt = get_expected_tpt(curr_tbl, rs_index);
+                        else if (table_type_matches(&tbl_type, other_tbl))
+                                tpt = get_expected_tpt(other_tbl, rs_index);
+                        else
+                                continue;
 
-        /* If not searching for new mode, increment success/failed counter
-         * ... these help determine when to start searching again */
-        if (lq_sta->stay_in_tbl) {
-                if (info->flags & IEEE80211_TX_STAT_AMPDU) {
-                        lq_sta->total_success += info->status.ampdu_ack_map;
-                        lq_sta->total_failed +=
-                             (info->status.ampdu_ack_len - info->status.ampdu_ack_map);
-                } else {
-                        if (status)
-                                lq_sta->total_success++;
+                        /* Constants mean 1 transmission, 0 successes */
+                        if (i < retries)
+                                rs_collect_tx_data(window, rs_index, tpt, 1,
+                                                0);
                         else
-                                lq_sta->total_failed++;
+                                rs_collect_tx_data(window, rs_index, tpt, 1,
+                                                legacy_success);
+                }
+
+                /* Update success/fail counts if not searching for new mode */
+                if (lq_sta->stay_in_tbl) {
+                        lq_sta->total_success += legacy_success;
+                        lq_sta->total_failed += retries + (1 - legacy_success);
                 }
         }
+        /* The last TX rate is cached in lq_sta; it's set in if/else above */
+        lq_sta->last_rate_n_flags = tx_rate;
 
         /* See if there's a better rate or modulation mode to try. */
         if (sta && sta->supp_rates[sband->band])
                 rs_rate_scale_perform(priv, skb, sta, lq_sta);
-out:
-        return;
 }
 
 /*