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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> <157d21fc-4745-4fa3-b7b1-b9f33e2e926e@altera.com> <20250925185230.62b4e2a5@kernel.org> Content-Language: en-US From: "G Thomas, Rohan" In-Reply-To: <20250925185230.62b4e2a5@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: MA0PR01CA0121.INDPRD01.PROD.OUTLOOK.COM (2603:1096:a01:11d::11) 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_|LV3PR03MB7753:EE_ X-MS-Office365-Filtering-Correlation-Id: 559d73b5-1685-4ff2-7ebf-08ddfd1c69c7 X-MS-Exchange-AtpMessageProperties: SA X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|376014|7416014; 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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 > > And the packet arrives at the driver with only the .1Q ID 200 pushed? > Yes, the packet arrives the driver with only 802.1Q ID. [ 210.192912] stmmaceth 10830000.ethernet eth0: >>> frame to be transmitted: [ 210.192917] len = 46 byte, buf addr: 0x0000000067c78222 [ 210.192923] 00000000: xx xx xx xx xx xx xx xx xx xx xx xx 81 00 00 c8 [ 210.192928] 00000010: 08 06 00 01 08 00 06 04 00 02 46 9b 06 1b 5b b6 [ 210.192931] 00000020: c0 a8 04 0a c8 a3 62 0e d7 04 c0 a8 04 0b > Indeed, that looks like a problem with the driver+HW interaction. > IDK what the right terminology is but IIRC VLAN 0 is not a real VLAN, > just an ID reserved for frames that don't have a VLAN ID but want to > use the priority field. Which explains why it "works", receiver just > ignores that tag. But it's definitely not correct because switches > on the network will no see the real C-TAG after the S-TAG is stripped. Yes, we are trying to figure out the right configuration for the driver so that the right tag is inserted by the driver for double and single VLANs. Based on the register configuration options for MAC_VLAN_Incl and MAC_Inner_VLAN_Incl registers and descriptor configuration options available, the hardware may not support simultaneous offloading of STAG for 802.1AD double-tagged packets and CTAG for 802.1Q single-tagged packets. If that is the case disable STAG insertion offloading may be the right approach. Best Regards, Rohan