ath9k: Handle different TX and RX streams properly.

This patch fixes an issue when the TX and RX streams are different.
Signed-off-by: Senthil Balasubramanian <senthilkumar@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -889,6 +889,7 @@ static void setup_ht_cap(struct ath_softc *sc,
 {
 #define	ATH9K_HT_CAP_MAXRXAMPDU_65536 0x3	/* 2 ^ 16 */
 #define	ATH9K_HT_CAP_MPDUDENSITY_8 0x6		/* 8 usec */
+	u8 tx_streams, rx_streams;
 
 	ht_info->ht_supported = true;
 	ht_info->cap = IEEE80211_HT_CAP_SUP_WIDTH_20_40 |
@@ -901,21 +902,22 @@ static void setup_ht_cap(struct ath_softc *sc,
 
 	/* set up supported mcs set */
 	memset(&ht_info->mcs, 0, sizeof(ht_info->mcs));
+	tx_streams = !(sc->tx_chainmask & (sc->tx_chainmask - 1)) ? 1 : 2;
+	rx_streams = !(sc->rx_chainmask & (sc->rx_chainmask - 1)) ? 1 : 2;
 
-	switch(sc->rx_chainmask) {
-	case 1:
-		ht_info->mcs.rx_mask[0] = 0xff;
-		break;
-	case 3:
-	case 5:
-	case 7:
-	default:
-		ht_info->mcs.rx_mask[0] = 0xff;
-		ht_info->mcs.rx_mask[1] = 0xff;
-		break;
+	if (tx_streams != rx_streams) {
+		DPRINTF(sc, ATH_DBG_CONFIG, "TX streams %d, RX streams: %d\n",
+			tx_streams, rx_streams);
+		ht_info->mcs.tx_params |= IEEE80211_HT_MCS_TX_RX_DIFF;
+		ht_info->mcs.tx_params |= ((tx_streams - 1) <<
+				IEEE80211_HT_MCS_TX_MAX_STREAMS_SHIFT);
 	}
 
-	ht_info->mcs.tx_params = IEEE80211_HT_MCS_TX_DEFINED;
+	ht_info->mcs.rx_mask[0] = 0xff;
+	if (rx_streams >= 2)
+		ht_info->mcs.rx_mask[1] = 0xff;
+
+	ht_info->mcs.tx_params |= IEEE80211_HT_MCS_TX_DEFINED;
 }
 
 static void ath9k_bss_assoc_info(struct ath_softc *sc,