net: ethernet: mtk_eth_soc: set PPE flow hash as skb hash if present

This improves GRO performance
Signed-off-by: Felix Fietkau <nbd@nbd.name>
[Ilya: Use MTK_RXD4_FOE_ENTRY instead of GENMASK(13, 0)]
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -19,6 +19,7 @@
 #include <linux/interrupt.h>
 #include <linux/pinctrl/devinfo.h>
 #include <linux/phylink.h>
+#include <linux/jhash.h>
 #include <net/dsa.h>
 
 #include "mtk_eth_soc.h"
@@ -1250,6 +1251,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 		struct net_device *netdev;
 		unsigned int pktlen;
 		dma_addr_t dma_addr;
+		u32 hash;
 		int mac;
 
 		ring = mtk_get_rx_ring(eth);
@@ -1319,6 +1321,12 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 		skb->protocol = eth_type_trans(skb, netdev);
 		bytes += pktlen;
 
+		hash = trxd.rxd4 & MTK_RXD4_FOE_ENTRY;
+		if (hash != MTK_RXD4_FOE_ENTRY) {
+			hash = jhash_1word(hash, 0);
+			skb_set_hash(skb, hash, PKT_HASH_TYPE_L4);
+		}
+
 		if (netdev->features & NETIF_F_HW_VLAN_CTAG_RX &&
 		    (trxd.rxd2 & RX_DMA_VTAG))
 			__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),