rt2x00: Implement tx mpdu aggregation

In order to implement tx mpdu aggregation we only have to implement
the ampdu_action callback such that mac80211 allows negotiation of
blockack sessions.

The hardware will handle everything on its own as long as the ampdu
flag in the TXWI struct is set up correctly and we translate the tx
status correctly.

For now, refuse requests to start rx aggregation.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index 339cc84..a914855 100644
--- a/drivers/net/wireless/rt2x00/rt2x00dev.c
+++ b/drivers/net/wireless/rt2x00/rt2x00dev.c
@@ -286,6 +286,21 @@
 			rt2x00dev->low_level_stats.dot11ACKFailureCount++;
 	}
 
+	/*
+	 * Every single frame has it's own tx status, hence report
+	 * every frame as ampdu of size 1.
+	 *
+	 * TODO: if we can find out how many frames were aggregated
+	 * by the hw we could provide the real ampdu_len to mac80211
+	 * which would allow the rc algorithm to better decide on
+	 * which rates are suitable.
+	 */
+	if (tx_info->flags & IEEE80211_TX_CTL_AMPDU) {
+		tx_info->flags |= IEEE80211_TX_STAT_AMPDU;
+		tx_info->status.ampdu_len = 1;
+		tx_info->status.ampdu_ack_len = success ? 1 : 0;
+	}
+
 	if (rate_flags & IEEE80211_TX_RC_USE_RTS_CTS) {
 		if (success)
 			rt2x00dev->low_level_stats.dot11RTSSuccessCount++;