ath9k: add LDPC support

LDPC is enabled by the rate control if the its determined
that the target peer supports LDPC. We would have already
intersected the HT capabilities so if our peer supports
LDPC so do we.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/rc.c

@@ -689,6 +689,15 @@ static void ath_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 	rate_table = sc->cur_rate_table;
 	rix = ath_rc_get_highest_rix(sc, ath_rc_priv, rate_table, &is_probe);
 
+	/*
+	 * If we're in HT mode and both us and our peer supports LDPC.
+	 * We don't need to check our own device's capabilities as our own
+	 * ht capabilities would have already been intersected with our peer's.
+	 */
+	if (conf_is_ht(&sc->hw->conf) &&
+	    (sta->ht_cap.cap & IEEE80211_HT_CAP_LDPC_CODING))
+		tx_info->flags |= IEEE80211_TX_CTL_LDPC;
+
 	if (is_probe) {
 		/* set one try for probe rates. For the
 		 * probes don't enable rts */