[PATCH] wifi: mt76: mt7921: do not support one stream on secondary antenna only

[Deren Wu]

mt7921 support following antenna combiantions only.
* primary + secondary (2x2)
* primary only        (1x1)

Since we cannot work on secondary antenna only, return error if the
antenna bitmap is 0x2 in .set_antenna().

For example:
iw phy0 set antenna 3 3 /* valid */
iw phy0 set antenna 1 1 /* valid */
iw phy0 set antenna 2 2 /* invalid */

Cc: stable at vger.kernel.org
Fixes: e0f9fdda81bd ("mt76: mt7921: add ieee80211_ops")
Suggested-by: Knox Chiou <knoxchiou at google.com>
Signed-off-by: Deren Wu <deren.wu at mediatek.com>
---
 drivers/net/wireless/mediatek/mt76/mt7921/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/main.c b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
index 0c9a472bc81a..6c971c30d6a1 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
@@ -1364,7 +1364,7 @@ mt7921_set_antenna(struct ieee80211_hw *hw, u32 tx_ant, u32 rx_ant)
 		return -EINVAL;
 
 	if ((BIT(hweight8(tx_ant)) - 1) != tx_ant)
-		tx_ant = BIT(ffs(tx_ant) - 1) - 1;
+		return -EINVAL;
 
 	mt7921_mutex_acquire(dev);
 
-- 
2.18.0