Subject: [PATCH] net: ethernet: mtk_eth_soc: fix parsing packets in GDM
From: Felix Fietkau <[email-masked]>
Date: Wed, 24 Mar 2021 02:30:52 +0100

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 <[email-masked]>
Signed-off-by: Pablo Neira Ayuso <[email-masked]>
---

--- 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"
 
@@ -1297,13 +1298,12 @@ 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) ||
+		    (trxd.rxd4 & RX_DMA_SPECIAL_TAG))
 			mac = 0;
-		} else {
-			mac = (trxd.rxd4 >> RX_DMA_FPORT_SHIFT) &
-				RX_DMA_FPORT_MASK;
-			mac--;
-		}
+		else
+			mac = ((trxd.rxd4 >> RX_DMA_FPORT_SHIFT) &
+			       RX_DMA_FPORT_MASK) - 1;
 
 		if (unlikely(mac < 0 || mac >= MTK_MAC_COUNT ||
 			     !eth->netdev[mac]))
@@ -2278,6 +2278,9 @@ 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
@@ -81,6 +81,7 @@
 
 /* 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)
@@ -318,6 +319,7 @@
 #define RX_DMA_L4_VALID_PDMA	BIT(30)		/* when PDMA is used */
 #define RX_DMA_FPORT_SHIFT	19
 #define RX_DMA_FPORT_MASK	0x7
+#define RX_DMA_SPECIAL_TAG	BIT(22)
 
 /* PHY Indirect Access Control registers */
 #define MTK_PHY_IAC		0x10004