iwlwifi: mvm: rs: consider a missing BA as a single tx failure

The fw now indicates missing BA with ampdu_ack_len=0.

This will make the whole aggregation being marked
as failed, although it's most likely not the case (and
only the BA itself was failed).

Consider this case as a single tx failure.
Signed-off-by: Eyal Shapira <eyalx.shapira@intel.com>
Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/iwlwifi/mvm/rs.c

@@ -1204,6 +1204,13 @@ void iwl_mvm_rs_tx_status(struct iwl_mvm *mvm, struct ieee80211_sta *sta,
 	 * first index into rate scale table.
 	 */
 	if (info->flags & IEEE80211_TX_STAT_AMPDU) {
+		/* ampdu_ack_len = 0 marks no BA was received. In this case
+		 * treat it as a single frame loss as we don't want the success
+		 * ratio to dip too quickly because a BA wasn't received
+		 */
+		if (info->status.ampdu_ack_len == 0)
+			info->status.ampdu_len = 1;
+
 		ucode_rate = le32_to_cpu(table->rs_table[0]);
 		rs_rate_from_ucode_rate(ucode_rate, info->band, &rate);
 		rs_collect_tx_data(lq_sta, curr_tbl, rate.index,