mac80211: reduce IEEE80211_TX_MAX_RATES

IEEE80211_TX_MAX_RATES can be reduced from 5 to 4 as there
is no current hardware supporting a rate chain with 5 multi
rate stages (mrr), so 4 mrr stages are sufficient.

The memory that is freed within the ieee80211_tx_info struct
will be used in the upcoming Transmission Power Control (TPC)
implementation.

Suggested-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
[reword commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

4 files changed, 11 insertions, 12 deletions

diff --git a/drivers/net/wireless/ath/carl9170/tx.c b/drivers/net/wireless/ath/carl9170/tx.c
index aed305177af6..ede0b572cebc 100644
--- a/drivers/net/wireless/ath/carl9170/tx.c
+++ b/drivers/net/wireless/ath/carl9170/tx.c
@@ -277,11 +277,11 @@ static void carl9170_tx_release(struct kref *ref)
                 return;
 
         BUILD_BUG_ON(
-            offsetof(struct ieee80211_tx_info, status.ampdu_ack_len) != 23);
+            offsetof(struct ieee80211_tx_info, status.ack_signal) != 20);
 
-        memset(&txinfo->status.ampdu_ack_len, 0,
+        memset(&txinfo->status.ack_signal, 0,
                sizeof(struct ieee80211_tx_info) -
-               offsetof(struct ieee80211_tx_info, status.ampdu_ack_len));
+               offsetof(struct ieee80211_tx_info, status.ack_signal));
 
         if (atomic_read(&ar->tx_total_queued))
                 ar->tx_schedule = true;
diff --git a/drivers/net/wireless/p54/txrx.c b/drivers/net/wireless/p54/txrx.c
index 82a1cac920bd..f38786e02623 100644
--- a/drivers/net/wireless/p54/txrx.c
+++ b/drivers/net/wireless/p54/txrx.c
@@ -422,11 +422,11 @@ static void p54_rx_frame_sent(struct p54_common *priv, struct sk_buff *skb)
          * Clear manually, ieee80211_tx_info_clear_status would
          * clear the counts too and we need them.
          */
-        memset(&info->status.ampdu_ack_len, 0,
+        memset(&info->status.ack_signal, 0,
                sizeof(struct ieee80211_tx_info) -
-               offsetof(struct ieee80211_tx_info, status.ampdu_ack_len));
+               offsetof(struct ieee80211_tx_info, status.ack_signal));
         BUILD_BUG_ON(offsetof(struct ieee80211_tx_info,
-                              status.ampdu_ack_len) != 23);
+                              status.ack_signal) != 20);
 
         if (entry_hdr->flags & cpu_to_le16(P54_HDR_FLAG_DATA_ALIGN))
                 pad = entry_data->align[0];
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index dc2a97af95e7..3f1b58cf9c8c 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -475,7 +475,7 @@ enum mac80211_rate_control_flags {
 #define IEEE80211_TX_INFO_RATE_DRIVER_DATA_SIZE 24
 
 /* maximum number of rate stages */
-#define IEEE80211_TX_MAX_RATES  5
+#define IEEE80211_TX_MAX_RATES  4
 
 /**
  * struct ieee80211_tx_rate - rate selection/status
@@ -563,11 +563,11 @@ struct ieee80211_tx_info {
                 } control;
                 struct {
                         struct ieee80211_tx_rate rates[IEEE80211_TX_MAX_RATES];
-                        u8 ampdu_ack_len;
                         int ack_signal;
+                        u8 ampdu_ack_len;
                         u8 ampdu_len;
                         u8 antenna;
-                        /* 14 bytes free */
+                        /* 21 bytes free */
                 } status;
                 struct {
                         struct ieee80211_tx_rate driver_rates[
@@ -634,7 +634,7 @@ ieee80211_tx_info_clear_status(struct ieee80211_tx_info *info)
                 info->status.rates[i].count = 0;
 
         BUILD_BUG_ON(
-            offsetof(struct ieee80211_tx_info, status.ampdu_ack_len) != 23);
+            offsetof(struct ieee80211_tx_info, status.ack_signal) != 20);
         memset(&info->status.ampdu_ack_len, 0,
                sizeof(struct ieee80211_tx_info) -
                offsetof(struct ieee80211_tx_info, status.ampdu_ack_len));
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 364a1e7b4afa..c9d2175d15c1 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -959,8 +959,7 @@ ieee80211_tx_h_fragment(struct ieee80211_tx_data *tx)
                         info->control.rates[1].idx = -1;
                         info->control.rates[2].idx = -1;
                         info->control.rates[3].idx = -1;
-                        info->control.rates[4].idx = -1;
-                        BUILD_BUG_ON(IEEE80211_TX_MAX_RATES != 5);
+                        BUILD_BUG_ON(IEEE80211_TX_MAX_RATES != 4);
                         info->flags &= ~IEEE80211_TX_CTL_RATE_CTRL_PROBE;
                 } else {
                         hdr->frame_control &= ~morefrags;