[PATCH net-next 27/30] net: dsa: mt7530: introduce BPDU trapping for MT7530 switch

[Vladimir Oltean]

On Mon, May 22, 2023 at 03:15:29PM +0300, arinc9.unal at gmail.com wrote:
> From: Arınç ÜNAL <arinc.unal at arinc9.com>
> 
> The MT753X switches are capable of trapping certain frames. Introduce
> trapping BPDUs to the CPU port for the MT7530 switch.
> 
> BPDUs will be trapped to the numerically smallest CPU port which is affine
> to the DSA conduit interface that is set up. The BPDUs won't necessarily be
> trapped to the CPU port the user port, which these BPDUs are received from,
> is affine to.
> 
> Tested-by: Arınç ÜNAL <arinc.unal at arinc9.com>
> Signed-off-by: Arınç ÜNAL <arinc.unal at 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 cd16911fcb01..2fb4b0bc6335 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -2223,6 +2223,10 @@ mt7530_setup(struct dsa_switch *ds)
>  	val |= MHWTRAP_MANUAL;
>  	mt7530_write(priv, MT7530_MHWTRAP, val);
>  
> +	/* Trap BPDUs to the CPU port */
> +	mt7530_rmw(priv, MT753X_BPC, MT753X_BPDU_PORT_FW_MASK,
> +		   MT753X_BPDU_CPU_ONLY);
> +

If the switch doesn't currently trap BPDUs, isn't STP broken?

ip link add br0 type bridge stp_state 1
(with or without a userspace helper installed at /sbin/bridge-stp
for more modern protocols than the original 802.1D STP)

>  	/* Enable and reset MIB counters */
>  	mt7530_mib_reset(ds);
>  
> -- 
> 2.39.2
>