From da17990421d79f1bfb4142f9d767fd33daecc3d8 Mon Sep 17 00:00:00 2001 From: Ovidiu Panait Date: Mon, 28 Sep 2026 20:34:41 +0000 Subject: [PATCH] net: stmmac: Disable S-Tag processing on dwmac4 Currently, hardware VLAN stripping is broken for 802.1ad tags. vlan_rx_hw() hardcodes ETH_P_8021Q when putting the hardware tag into the skb, rather than using the actual protocol from the packet. Because of this, packets that contain a 802.1ad outer tag are incorrectly passed up the stack as having an 802.1Q tag. This causes QinQ ping between two hosts to fail. vlan_rx_hw() is shared by dwxgmac2 and dwmac4: on dwxgmac2 the tag type is available in the RDES3 write-back descriptor (the ET_LT field), so the outer tag type can be determined based on that info. However, dwmac4 doesn't seem to provide the tag type. The Length/Type field in RDES3 only indicates whether the packet is single or double-tagged, not which tag type was stripped. Since dwmac4 cannot report the stripped tag type, it cannot support hardware S-Tag stripping correctly. Therefore, restrict the NETIF_F_HW_VLAN_STAG_RX and NETIF_F_HW_VLAN_STAG_FILTER advertisement to dwxgmac2 only. With this, 802.1ad tags are left in place and handled by the software VLAN path. Fixes: 750011e239a5 ("net: stmmac: Add support for HW-accelerated VLAN stripping") Signed-off-by: Ovidiu Panait Reviewed-by: Maxime Chevallier Link: https://patch.msgid.link/20260928203441.34876-6-ovidiu.panait.rb@renesas.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 13e11df7f4c8..77d2bffb8dc1 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -6268,7 +6268,7 @@ static netdev_features_t stmmac_fix_features(struct net_device *dev, if (priv->plat->bugged_jumbo && (dev->mtu > ETH_DATA_LEN)) features &= ~NETIF_F_CSUM_MASK; - if (dwmac_is_xmac(priv->plat->core_type)) { + if (priv->plat->core_type == DWMAC_CORE_XGMAC) { if (features & NETIF_F_HW_VLAN_CTAG_RX) features |= NETIF_F_HW_VLAN_STAG_RX; else @@ -8055,14 +8055,18 @@ static int __stmmac_dvr_probe(struct device *device, ndev->watchdog_timeo = msecs_to_jiffies(watchdog); #ifdef STMMAC_VLAN_TAG_USED /* Both mac100 and gmac support receive VLAN tag detection */ - ndev->features |= NETIF_F_HW_VLAN_CTAG_RX | NETIF_F_HW_VLAN_STAG_RX; + ndev->features |= NETIF_F_HW_VLAN_CTAG_RX; + if (priv->plat->core_type == DWMAC_CORE_XGMAC) + ndev->features |= NETIF_F_HW_VLAN_STAG_RX; + if (dwmac_is_xmac(priv->plat->core_type)) { ndev->hw_features |= NETIF_F_HW_VLAN_CTAG_RX; priv->hw->hw_vlan_en = true; } if (priv->dma_cap.vlhash) { ndev->features |= NETIF_F_HW_VLAN_CTAG_FILTER; - ndev->features |= NETIF_F_HW_VLAN_STAG_FILTER; + if (priv->plat->core_type == DWMAC_CORE_XGMAC) + ndev->features |= NETIF_F_HW_VLAN_STAG_FILTER; } if (priv->dma_cap.vlins) ndev->features |= NETIF_F_HW_VLAN_CTAG_TX;