wifi: mt76: mt7996: check txs format before getting skb by pid

The PPDU TXS does not include the error bit so it cannot use to report
status to mac80211. This patch fixes issue that STA wrongly detects if AP
is still alive.

Fixes: 2569ea53 ("wifi: mt76: mt7996: enable PPDU-TxS to host")
Signed-off-by: Peter Chiu <chui-hao.chiu@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7996/mac.c

@@ -1188,15 +1188,17 @@ mt7996_mac_add_txs_skb(struct mt7996_dev *dev, struct mt76_wcid *wcid,
 	struct ieee80211_tx_info *info;
 	struct sk_buff_head list;
 	struct rate_info rate = {};
-	struct sk_buff *skb;
+	struct sk_buff *skb = NULL;
 	bool cck = false;
 	u32 txrate, txs, mode, stbc;
 
 	txs = le32_to_cpu(txs_data[0]);
 
 	mt76_tx_status_lock(mdev, &list);
-	skb = mt76_tx_status_skb_get(mdev, wcid, pid, &list);
 
+	/* only report MPDU TXS */
+	if (le32_get_bits(txs_data[0], MT_TXS0_TXS_FORMAT) == 0) {
+		skb = mt76_tx_status_skb_get(mdev, wcid, pid, &list);
 		if (skb) {
 			info = IEEE80211_SKB_CB(skb);
 			if (!(txs & MT_TXS0_ACK_ERROR_MASK))
@@ -1208,6 +1210,7 @@ mt7996_mac_add_txs_skb(struct mt7996_dev *dev, struct mt76_wcid *wcid,
 
 			info->status.rates[0].idx = -1;
 		}
+	}
 
 	if (mtk_wed_device_active(&dev->mt76.mmio.wed) && wcid->sta) {
 		struct ieee80211_sta *sta;