From: Felix Fietkau <nbd@nbd.name>
Date: Sun, 13 Sep 2020 08:17:02 +0200
Subject: [PATCH] net: ethernet: mtk_eth_soc: fix parsing packets in GDM

When using DSA, set the special tag in GDM ingress control to allow the MAC
to parse packets properly earlier. This affects rx DMA source port reporting.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/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 <net/dsa.h>
 
 #include "mtk_eth_soc.h"
 
@@ -1240,12 +1241,14 @@ static int mtk_poll_rx(struct napi_struc
 	u8 *data, *new_data;
 	struct mtk_rx_dma *rxd, trxd;
 	int done = 0, bytes = 0;
+	bool uses_dsa = eth->netdev[0] && netdev_uses_dsa(eth->netdev[0]);
 
 	while (done < budget) {
 		struct net_device *netdev;
 		unsigned int pktlen;
 		dma_addr_t dma_addr;
 		int mac;
+		u16 hash;
 
 		ring = mtk_get_rx_ring(eth);
 		if (unlikely(!ring))
@@ -1259,13 +1262,13 @@ static int mtk_poll_rx(struct napi_struc
 			break;
 
 		/* find out which mac the packet come from. values start at 1 */
-		if (MTK_HAS_CAPS(eth->soc->caps, MTK_SOC_MT7628)) {
+		if (MTK_HAS_CAPS(eth->soc->caps, MTK_SOC_MT7628))
 			mac = 0;
-		} else {
-			mac = (trxd.rxd4 >> RX_DMA_FPORT_SHIFT) &
-				RX_DMA_FPORT_MASK;
-			mac--;
-		}
+		else if (uses_dsa)
+			mac = !(trxd.rxd4 >> 22);
+		else
+			mac = ((trxd.rxd4 >> RX_DMA_FPORT_SHIFT) &
+			       RX_DMA_FPORT_MASK) - 1;
 
 		if (unlikely(mac < 0 || mac >= MTK_MAC_COUNT ||
 			     !eth->netdev[mac]))
@@ -2247,6 +2250,9 @@ static void mtk_gdm_config(struct mtk_et
 
 		val |= config;
 
+		if (!i && eth->netdev[0] && netdev_uses_dsa(eth->netdev[0]))
+			val |= MTK_GDMA_SPECIAL_TAG;
+
 		mtk_w32(eth, val, MTK_GDMA_FWD_CFG(i));
 	}
 	/* Reset and enable PSE */
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -82,6 +82,7 @@
 
 /* GDM Exgress Control Register */
 #define MTK_GDMA_FWD_CFG(x)	(0x500 + (x * 0x1000))
+#define MTK_GDMA_SPECIAL_TAG	BIT(24)
 #define MTK_GDMA_ICS_EN		BIT(22)
 #define MTK_GDMA_TCS_EN		BIT(21)
 #define MTK_GDMA_UCS_EN		BIT(20)