[PATCH net] net: dsa: mt7530: fix handling of 802.1X PAE frames

[Vladimir Oltean]

On Sun, Aug 13, 2023 at 01:59:17PM +0300, Arınç ÜNAL wrote:
> 802.1X PAE frames are link-local frames, therefore they must be trapped to
> the CPU port. Currently, the MT753X switches treat 802.1X PAE frames as
> regular multicast frames, therefore flooding them to user ports. To fix
> this, set 802.1X PAE frames to be trapped to the CPU port(s).
> 
> Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
> Signed-off-by: Arınç ÜNAL <arinc.unal at arinc9.com>
> ---
>  drivers/net/dsa/mt7530.c | 4 ++++
>  drivers/net/dsa/mt7530.h | 2 ++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index 38b3c6dda386..b8bb9f3b3609 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -1006,6 +1006,10 @@ mt753x_trap_frames(struct mt7530_priv *priv)
>  	mt7530_rmw(priv, MT753X_BPC, MT753X_BPDU_PORT_FW_MASK,
>  		   MT753X_BPDU_CPU_ONLY);
>  
> +	/* Trap 802.1X PAE frames to the CPU port(s) */
> +	mt7530_rmw(priv, MT753X_BPC, MT753X_PAE_PORT_FW_MASK,
> +		   MT753X_PAE_PORT_FW(MT753X_BPDU_CPU_ONLY));
> +

In the interest of efficiency, this could have been merged with the
previous write to MT753X_BPC, which would save some MDIO transactions:

	mt7530_rmw(priv, MT753X_BPC,
		   MT753X_BPDU_PORT_FW_MASK | MT753X_PAE_PORT_FW_MASK,
		   MT753X_BPDU_CPU_ONLY |
		   MT753X_PAE_PORT_FW(MT753X_BPDU_CPU_ONLY));

In the interest of readability, this is probably fine too.

Reviewed-by: Vladimir Oltean <olteanv at gmail.com>

>  	/* Trap LLDP frames with :0E MAC DA to the CPU port(s) */
>  	mt7530_rmw(priv, MT753X_RGAC2, MT753X_R0E_PORT_FW_MASK,
>  		   MT753X_R0E_PORT_FW(MT753X_BPDU_CPU_ONLY));
> diff --git a/drivers/net/dsa/mt7530.h b/drivers/net/dsa/mt7530.h
> index 08045b035e6a..17e42d30fff4 100644
> --- a/drivers/net/dsa/mt7530.h
> +++ b/drivers/net/dsa/mt7530.h
> @@ -66,6 +66,8 @@ enum mt753x_id {
>  /* Registers for BPDU and PAE frame control*/
>  #define MT753X_BPC			0x24
>  #define  MT753X_BPDU_PORT_FW_MASK	GENMASK(2, 0)
> +#define  MT753X_PAE_PORT_FW_MASK	GENMASK(18, 16)
> +#define  MT753X_PAE_PORT_FW(x)		FIELD_PREP(MT753X_PAE_PORT_FW_MASK, x)
>  
>  /* Register for :03 and :0E MAC DA frame control */
>  #define MT753X_RGAC2			0x2c
> -- 
> 2.39.2
>