target/linux/mediatek/patches-5.4/730-net-ethernet-mtk_eth_soc-add-mtk-dsa-tag-rx-offload.patch

--- linux-5.4.77.orig/net/dsa/tag_mtk.c
+++ linux-5.4.77/net/dsa/tag_mtk.c
@@ -73,22 +73,28 @@ static struct sk_buff *mtk_tag_rcv(struc
 	bool is_multicast_skb = is_multicast_ether_addr(dest) &&
 				!is_broadcast_ether_addr(dest);
 
-	if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
-		return NULL;
+	if (dev->features & NETIF_F_HW_VLAN_CTAG_RX) {
+		hdr = ntohs(skb->vlan_proto);
+		skb->vlan_proto = 0;
+		skb->vlan_tci = 0;
+	} else {
+		if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
+			return NULL;
 
-	/* The MTK header is added by the switch between src addr
-	 * and ethertype at this point, skb->data points to 2 bytes
-	 * after src addr so header should be 2 bytes right before.
-	 */
-	phdr = (__be16 *)(skb->data - 2);
-	hdr = ntohs(*phdr);
+		/* The MTK header is added by the switch between src addr
+		 * and ethertype at this point, skb->data points to 2 bytes
+		 * after src addr so header should be 2 bytes right before.
+		 */
+		phdr = (__be16 *)(skb->data - 2);
+		hdr = ntohs(*phdr);
 
-	/* Remove MTK tag and recalculate checksum. */
-	skb_pull_rcsum(skb, MTK_HDR_LEN);
+		/* Remove MTK tag and recalculate checksum. */
+		skb_pull_rcsum(skb, MTK_HDR_LEN);
 
-	memmove(skb->data - ETH_HLEN,
-		skb->data - ETH_HLEN - MTK_HDR_LEN,
-		2 * ETH_ALEN);
+		memmove(skb->data - ETH_HLEN,
+			skb->data - ETH_HLEN - MTK_HDR_LEN,
+			2 * ETH_ALEN);
+	}
 
 	/* Get source port information */
 	port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);