From: Daniel Golle <daniel@makrotopia.org>
To: Joris Vaisvila <joey@tinyisr.com>
Cc: netdev@vger.kernel.org, horms@kernel.org, pabeni@redhat.com,
kuba@kernel.org, edumazet@google.com, davem@davemloft.net,
olteanv@gmail.com, "Andrew Lunn" <andrew@lunn.ch>,
devicetree@vger.kernel.org, "Rob Herring" <robh@kernel.org>,
"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
"Conor Dooley" <conor+dt@kernel.org>,
"Arınç ÜNAL" <arinc.unal@arinc9.com>,
"Landen Chao" <Landen.Chao@mediatek.com>,
"DENG Qingfang" <dqfext@gmail.com>,
"Sean Wang" <sean.wang@mediatek.com>
Subject: Re: [PATCH net-next v5 3/4] net: dsa: initial MT7628 tagging driver
Date: Sat, 13 Jun 2026 19:49:53 +0100 [thread overview]
Message-ID: <ai2mUbNT8acedvc0@makrotopia.org> (raw)
In-Reply-To: <20260613181845.111877-4-joey@tinyisr.com>
On Sat, Jun 13, 2026 at 09:18:44PM +0300, Joris Vaisvila wrote:
> Add support for the MT7628 embedded switch's tag.
>
> The MT7628 tag is merged with the VLAN TPID field when a VLAN is
> appended by the switch hardware. It is not installed if the VLAN tag is
> already there on ingress. Due to this hardware quirk the tag cannot be
> trusted for port 0 if we don't know that the VLAN was added by the
> hardware. As a workaround for this the switch is configured to always
> append the port PVID tag even if the incoming packet is already tagged.
> The tagging driver can then trust that the tag is always accurate and
> the whole VLAN tag can be removed on ingress as it's only metadata for
> the tagger.
>
> On egress the MT7628 tag allows precise TX, but the correct VLAN tag
> from tag_8021q is still appended or the switch will not forward the
> packet.
>
> Signed-off-by: Joris Vaisvila <joey@tinyisr.com>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Daniel Golle <daniel@makrotopia.org>
next prev parent reply other threads:[~2026-06-13 18:49 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-13 18:18 [PATCH net-next v5 0/4] net: dsa: mt7628 embedded switch initial support Joris Vaisvila
2026-06-13 18:18 ` [PATCH net-next v5 1/4] dt-bindings: net: dsa: add MT7628 ESW Joris Vaisvila
2026-06-13 18:18 ` [PATCH net-next v5 2/4] net: phy: mediatek: add phy driver for MT7628 built-in Fast Ethernet PHYs Joris Vaisvila
2026-06-13 18:49 ` Daniel Golle
2026-06-13 18:18 ` [PATCH net-next v5 3/4] net: dsa: initial MT7628 tagging driver Joris Vaisvila
2026-06-13 18:49 ` Daniel Golle [this message]
2026-06-13 18:18 ` [PATCH net-next v5 4/4] net: dsa: initial support for MT7628 embedded switch Joris Vaisvila
2026-06-13 18:52 ` Daniel Golle
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