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Miller" , Eric Dumazet , Paolo Abeni , Maxime Coquelin , Alexandre Torgue , Jose Abreu , Rohan G Thomas , netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Matthew Gerlach , "Ng, Boon Khai" References: <20250915-qbv-fixes-v2-0-ec90673bb7d4@altera.com> <20250915-qbv-fixes-v2-2-ec90673bb7d4@altera.com> <20250917154920.7925a20d@kernel.org> <20250917155412.7b2af4f1@kernel.org> <20250924160535.12c14ae9@kernel.org> Content-Language: en-US From: "G Thomas, Rohan" In-Reply-To: <20250924160535.12c14ae9@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: MA0PR01CA0106.INDPRD01.PROD.OUTLOOK.COM (2603:1096:a01:af::16) To DM6PR03MB5371.namprd03.prod.outlook.com (2603:10b6:5:24c::21) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM6PR03MB5371:EE_|BY5PR03MB5362:EE_ X-MS-Office365-Filtering-Correlation-Id: 3736785e-7549-438b-47b0-08ddfc232a2f X-MS-Exchange-AtpMessageProperties: SA X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|7416014|376014|1800799024; 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So I think we should do the same thing here? >>> >>> I suppose the double tagging depends on the exact SKU but first check >>> looks unnecessary. Maybe stmmac_vlan_insert() should return the number >>> of vlans it decided to insert? >>> >> >> I overlooked the behavior of stmmac_vlan_insert(). It seems the hardware >> supports inserting only one VLAN tag at a time, with the default setting >> being SVLAN for 802.1AD and CVLAN for 802.1Q. I'll update the patch to >> simply add VLAN_HLEN when stmmac_vlan_insert() returns true. Please let >> me know if you have any further concerns. > > SG, no further concerns. > > Please make sure to CC "Ng, Boon Khai" > who wrote the VLAN support (IIRC). While testing 802.1AD with XGMAC hardware using a simple ping test, I observed an unexpected behavior: the hardware appears to insert an additional 802.1Q CTAG with VLAN ID 0. Despite this, the ping test functions correctly. Here’s a snapshot from the pcap captured at the remote end. Outer VLAN tag used is 100 and inner VLAN tag used is 200. Frame 1: 110 bytes on wire (880 bits), 110 bytes captured (880 bits) Ethernet II, Src: (), Dst: () IEEE 802.1ad, ID: 100 802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 0(unexpected) 802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 200 Internet Protocol Version 4, Src: 192.168.4.10, Dst: 192.168.4.11 Internet Control Message Protocol I’m working with Boon Khai to understand whether this behavior is expected or SKU-specific. Any insights will be helpful for us. Best Regards, Rohan