[PATCH net] net: ethernet: mtk_eth_soc: disable hardware DSA untagging for second MAC

[Arınç ÜNAL]

According to my tests on MT7621AT and MT7623NI SoCs, hardware DSA untagging
won't work on the second MAC. Therefore, disable this feature when the
second MAC of the MT7621 and MT7623 SoCs is being used.

Fixes: 2d7605a72906 ("net: ethernet: mtk_eth_soc: enable hardware DSA untagging")
Link: https://lore.kernel.org/netdev/6249fc14-b38a-c770-36b4-5af6d41c21d3@arinc9.com/
Tested-by: Arınç ÜNAL <arinc.unal at arinc9.com>
Signed-off-by: Arınç ÜNAL <arinc.unal at arinc9.com>
---

The MTK_GMAC1_TRGMII capability is only on the MT7621 and MT7623 SoCs which
I see this problem on. I'm new to coding so I took an educated guess from
the use of MTK_NETSYS_V2 to disable this feature altogether for MT7986 SoC.

Arınç

---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 801deac58bf7..f1cb1efc94cf 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -3243,7 +3243,8 @@ static int mtk_open(struct net_device *dev)
 	struct mtk_eth *eth = mac->hw;
 	int i, err;
 
-	if (mtk_uses_dsa(dev) && !eth->prog) {
+	if ((mtk_uses_dsa(dev) && !eth->prog) &&
+	    !(mac->id == 1 && MTK_HAS_CAPS(eth->soc->caps, MTK_GMAC1_TRGMII))) {
 		for (i = 0; i < ARRAY_SIZE(eth->dsa_meta); i++) {
 			struct metadata_dst *md_dst = eth->dsa_meta[i];
 
@@ -3260,7 +3261,8 @@ static int mtk_open(struct net_device *dev)
 		}
 	} else {
 		/* Hardware special tag parsing needs to be disabled if at least
-		 * one MAC does not use DSA.
+		 * one MAC does not use DSA, or the second MAC of the MT7621 and
+		 * MT7623 SoCs is being used.
 		 */
 		u32 val = mtk_r32(eth, MTK_CDMP_IG_CTRL);
 		val &= ~MTK_CDMP_STAG_EN;
-- 
2.37.2