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From: DENG Qingfang <>
To: Vladimir Oltean <>
Cc: Sean Wang <>,
	Landen Chao <>,
	Andrew Lunn <>,
	Vivien Didelot <>,
	Florian Fainelli <>,
	"David S. Miller" <>,
	Jakub Kicinski <>,
	Matthias Brugger <>,
	netdev <>,
	Linux ARM <>,
	"moderated list:ARM/Mediatek SoC support" 
	linux-kernel <>
Subject: Re: [RFC net-next 2/2] net: dsa: mt7530: trap packets from standalone ports to the CPU
Date: Fri, 30 Jul 2021 23:45:41 +0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20210729165027.okmfa3ulpd3e6gte@skbuf>

On Fri, Jul 30, 2021 at 12:50 AM Vladimir Oltean <> wrote:
> I have the MT7621 GSW, and sadly this reference manual isn't the best in
> explaining what is and what is not possible. For example, I am still not
> clear what is meant by "VID1" and "VID0". Is "VID1" the inner (customer)
> VLAN tag, and "VID0" the outer (service) VLAN tag, or "VID1" means the
> actual VLAN ID 1?
> And the bits 3:1 of VAWD1 (VLAN table access register) indicate a FID
> field per VLAN. I cannot find the piece that you quoted in this manual.
> But what I expect to happen for a Transparent Port is that the packets
> are always classified to that port's PVID, and the VLAN Table is looked
> up with that PVID. There, it will find the FID, which this driver
> currently always configures as zero. In my manual's description, in the
> "Transparent Port" chapter, it does explicitly say:
>         VID0 and VID1 will store PVID as the default VID which is used
>         to look up the VLAN table.
> So I get the impression that the phrase "the VLAN table is not applicable"
> is not quite correct, but I might be wrong...

Alright, I think I've made some progress.
In the current code, we only use two combinations to toggle user
ports' VLAN awareness: one is PCR.PORT_VLAN set to port matrix mode
with PVC.VLAN_ATTR set to transparent port, the other is PCR.PORT_VLAN
set to security mode with PVC.VLAN_ATTR set to user port.

It turns out that only PVC.VLAN_ATTR contributes to VLAN awareness.
Port matrix mode just skips the VLAN table lookup. The reference
manual is somehow misleading when describing PORT_VLAN modes (See Page
17 of MT7531 Reference Manual, available at It states that
PORT_MEM (VLAN port member) is used for destination if the VLAN table
lookup hits, but actually it uses **PORT_MEM & PORT_MATRIX** (bitwise
AND of VLAN port member and port matrix) instead, which means we can
have two or more separate VLAN-aware bridges with the same PVID and
traffic won't leak between them.

So I came up with a solution: Set PORT_VLAN to fallback mode when in
VLAN-unaware mode, this way, even VLAN-unaware bridges will use
independent VLAN filtering. Then assign all standalone ports to a
reserved VLAN.

  reply	other threads:[~2021-07-30 15:45 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-28 17:53 [RFC net-next 0/2] mt7530 software fallback bridging fix DENG Qingfang
2021-07-28 17:53 ` [RFC net-next 1/2] net: dsa: tag_mtk: skip address learning on transmit to standalone ports DENG Qingfang
2021-07-28 18:37   ` Vladimir Oltean
2021-07-30 16:24     ` Vladimir Oltean
2021-07-30 17:32       ` DENG Qingfang
2021-07-30 17:39         ` Vladimir Oltean
2021-07-30 17:41           ` Vladimir Oltean
2021-07-30 17:58             ` DENG Qingfang
2021-07-30 19:00       ` DENG Qingfang
2021-07-30 19:07         ` Vladimir Oltean
2021-07-30 19:25           ` DENG Qingfang
2021-07-30 19:30             ` Vladimir Oltean
2021-07-28 17:53 ` [RFC net-next 2/2] net: dsa: mt7530: trap packets from standalone ports to the CPU DENG Qingfang
2021-07-28 18:47   ` Vladimir Oltean
2021-07-29 15:28   ` Vladimir Oltean
2021-07-29 16:11     ` DENG Qingfang
2021-07-29 16:50       ` Vladimir Oltean
2021-07-30 15:45         ` DENG Qingfang [this message]
2021-07-30 15:58           ` DENG Qingfang
2021-07-30 16:18           ` Vladimir Oltean
2021-07-30 17:21             ` DENG Qingfang
2021-07-30 17:35               ` Vladimir Oltean
2021-07-30 17:51                 ` DENG Qingfang
2021-07-28 18:08 ` [RFC net-next 0/2] mt7530 software fallback bridging fix Vladimir Oltean

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