netdev - Re: [PATCH 1/3] net: ethernet: ti: am65-cpsw: Fix max mtu to fit ethernet frames

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Date: Tue, 2 Jan 2024 15:23:37 +0530
From: Siddharth Vadapalli <s-vadapalli@...com>
To: Sanjuán García, Jorge
	<Jorge.SanjuanGarcia@...gon.com>
CC: "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com"
	<edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>,
        <s-vadapalli@...com>
Subject: Re: [PATCH 1/3] net: ethernet: ti: am65-cpsw: Fix max mtu to fit
 ethernet frames

Hello,

On 02-01-2024 13:49, Sanjuán García, Jorge wrote:
> The value of AM65_CPSW_MAX_PACKET_SIZE represents the maximum length
> of a received frame. This value is written to the register
> AM65_CPSW_PORT_REG_RX_MAXLEN.
> 
> The maximum MTU configured on the network device should then leave
> some room for the ethernet headers and frame check. Otherwise, if
> the network interface is configured to its maximum mtu possible,
> the frames will be larger than AM65_CPSW_MAX_PACKET_SIZE and will
> get dropped as oversized.
> 
> Fixes: 93a76530316a ("net: ethernet: ti: introduce am65x/j721e gigabit eth 
> subsystem driver")
> Signed-off-by: Jorge Sanjuan Garcia <jorge.sanjuangarcia@...gon.com>

Please use [PATCH net] as the subject prefix for patches which are
posted as Bug Fixes. Apart from that, this patch looks good to me.

Reviewed-by: Siddharth Vadapalli <s-vadapalli@...com>

> ---
>   drivers/net/ethernet/ti/am65-cpsw-nuss.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c 
> b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
> index 7651f90f51f2..378d69b8cb14 100644
> --- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
> +++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
> @@ -2196,7 +2196,8 @@ am65_cpsw_nuss_init_port_ndev(struct am65_cpsw_common 
> *common, u32 port_idx)
>           eth_hw_addr_set(port->ndev, port->slave.mac_addr);
> 
>           port->ndev->min_mtu = AM65_CPSW_MIN_PACKET_SIZE;
> -       port->ndev->max_mtu = AM65_CPSW_MAX_PACKET_SIZE;
> +       port->ndev->max_mtu = AM65_CPSW_MAX_PACKET_SIZE -
> +                             (VLAN_ETH_HLEN + ETH_FCS_LEN);
>           port->ndev->hw_features = NETIF_F_SG |
>                                     NETIF_F_RXCSUM |
>                                     NETIF_F_HW_CSUM |

...

-- 
Regards,
Siddharth.