Re: [PATCH] net: xilinx: Reject broadcast and multicast packets in AXI Ethernet MAC

[Michal Simek <michal.simek@amd.com>]

On 3/23/26 17:09, Michal Simek wrote:
> Set the XAE_RAF_BCSTREJ_MASK bit in the Reset and Address Filter (RAF)
> register during hardware initialization to make the MAC drop incoming
> frames with broadcast destination address. This avoids unnecessary
> broadcast traffic processing by the CPU.
> 
> Additionally, when IPv6 is not enabled (CONFIG_IPV6), also set the
> XAE_RAF_MCSTREJ_MASK bit to reject multicast frames. Multicast
> rejection is skipped when IPv6 is configured because IPv6 Neighbor
> Discovery and DHCPv6 rely on multicast.
> 
> Expose the RAF register (offset 0x0) in struct axi_regs which was
> previously hidden in a reserved array.
> 
> Signed-off-by: Michal Simek <michal.simek@amd.com>
> ---
> 
>   drivers/net/xilinx_axi_emac.c | 20 +++++++++++++++++++-
>   1 file changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/xilinx_axi_emac.c b/drivers/net/xilinx_axi_emac.c
> index e9cc5db52d25..1ea81fe1830a 100644
> --- a/drivers/net/xilinx_axi_emac.c
> +++ b/drivers/net/xilinx_axi_emac.c
> @@ -28,6 +28,10 @@
>   #define XAE_EMMC_LINKSPD_100	0x40000000 /* Link Speed mask for 100 Mbit */
>   #define XAE_EMMC_LINKSPD_1000	0x80000000 /* Link Speed mask for 1000 Mbit */
>   
> +/* Reset and Address Filter (RAF) Register bit definitions */
> +#define XAE_RAF_MCSTREJ_MASK	0x00000002 /* Reject rx multicast dst addr */
> +#define XAE_RAF_BCSTREJ_MASK	0x00000004 /* Reject rx broadcast dst addr */
> +
>   /* Interrupt Status/Enable/Mask Registers bit definitions */
>   #define XAE_INT_RXRJECT_MASK	0x00000008 /* Rx frame rejected */
>   #define XAE_INT_MGTRDY_MASK	0x00000080 /* MGT clock Lock */
> @@ -153,7 +157,8 @@ static struct axidma_bd tx_bd __attribute((aligned(DMAALIGN)));
>   static struct axidma_bd rx_bd __attribute((aligned(DMAALIGN)));
>   
>   struct axi_regs {
> -	u32 reserved[3];
> +	u32 raf; /* 0x0: Reset and Address Filter */
> +	u32 reserved[2];
>   	u32 is; /* 0xC: Interrupt status */
>   	u32 reserved2;
>   	u32 ie; /* 0x14: Interrupt enable */
> @@ -528,6 +533,19 @@ static int axi_ethernet_init(struct axidma_priv *priv)
>   	/* Set default MDIO divisor */
>   	writel(XAE_MDIO_DIV_DFT | XAE_MDIO_MC_MDIOEN_MASK, &regs->mdio_mc);
>   
> +	/*
> +	 * Reject broadcast and multicast frames at MAC level to reduce
> +	 * unnecessary traffic processing. Multicast rejection is only
> +	 * enabled when IPv6 is not configured because IPv6 Neighbor
> +	 * Discovery and DHCPv6 rely on multicast.
> +	 */
> +	if (!IS_ENABLED(CONFIG_IPV6))
> +		writel(readl(&regs->raf) | XAE_RAF_MCSTREJ_MASK |
> +		       XAE_RAF_BCSTREJ_MASK, &regs->raf);
> +	else
> +		writel(readl(&regs->raf) | XAE_RAF_BCSTREJ_MASK,
> +		       &regs->raf);
> +
>   	debug("axiemac: InitHw done\n");
>   	return 0;
>   }

Applied.
M