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Date:   Wed, 14 Jun 2023 23:50:08 +0300
From:   Vladimir Oltean <olteanv@gmail.com>
To:     arinc9.unal@gmail.com
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        Daniel Golle <daniel@makrotopia.org>,
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        Andrew Lunn <andrew@lunn.ch>,
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        Eric Dumazet <edumazet@google.com>,
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        Paolo Abeni <pabeni@redhat.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Russell King <linux@armlinux.org.uk>,
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        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org
Subject: Re: [PATCH net v4 4/7] net: dsa: mt7530: fix handling of BPDUs on
 MT7530 switch
Message-ID: <20230614205008.czro45ogsc4c6sb5@skbuf>
References: <20230612075945.16330-1-arinc.unal@arinc9.com>
 <20230612075945.16330-5-arinc.unal@arinc9.com>
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On Mon, Jun 12, 2023 at 10:59:42AM +0300, arinc9.unal@gmail.com wrote:
> From: Arınç ÜNAL <arinc.unal@arinc9.com>
> 
> BPDUs are link-local frames, therefore they must be trapped to the CPU
> port. Currently, the MT7530 switch treats BPDUs as regular multicast
> frames, therefore flooding them to user ports. To fix this, set BPDUs to be
> trapped to the CPU port.
> 
> BPDUs received from a user port will be trapped to the numerically smallest
> CPU port which is affine to the DSA conduit interface that is up.
> 
> Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
> Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
> ---
>  drivers/net/dsa/mt7530.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index 2bde2fdb5fba..e4c169843f2e 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -2259,6 +2259,10 @@ mt7530_setup(struct dsa_switch *ds)
>  
>  	priv->p6_interface = PHY_INTERFACE_MODE_NA;
>  
> +	/* Trap BPDUs to the CPU port */
> +	mt7530_rmw(priv, MT753X_BPC, MT753X_BPDU_PORT_FW_MASK,
> +		   MT753X_BPDU_CPU_ONLY);
> +
>  	/* Enable and reset MIB counters */
>  	mt7530_mib_reset(ds);
>  
> -- 
> 2.39.2
> 

Where have you seen the BPC register in the memory map of MT7530 or MT7621?