Re: [net-next PATCH 1/2] net: ravb: Fix maximum MTU for GbEth devices

[Niklas Söderlund]

Hi Paul,

Thanks for your work.

On 2024-06-15 11:30:37 +0100, Paul Barker wrote:
> The datasheets for all SoCs using the GbEth IP specify a maximum
> transmission frame size of 1.5 kByte. I've confirmed through internal
> discussions that support for 1522 byte frames has been validated, which
> allows us to support the default MTU of 1500 bytes after reserving space
> for the Ethernet header, frame checksums and an optional VLAN tag.
> 
> Fixes: 2e95e08ac009 ("ravb: Add rx_max_buf_size to struct ravb_hw_info")
> Signed-off-by: Paul Barker <paul.barker.ct@xxxxxxxxxxxxxx>

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>

> ---
>  drivers/net/ethernet/renesas/ravb.h      | 1 +
>  drivers/net/ethernet/renesas/ravb_main.c | 6 +++++-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
> index 6b2444d31fcc..e592e89b0d96 100644
> --- a/drivers/net/ethernet/renesas/ravb.h
> +++ b/drivers/net/ethernet/renesas/ravb.h
> @@ -1051,6 +1051,7 @@ struct ravb_hw_info {
>  	netdev_features_t net_features;
>  	int stats_len;
>  	u32 tccr_mask;
> +	u32 tx_max_frame_size;
>  	u32 rx_max_frame_size;
>  	u32 rx_buffer_size;
>  	u32 rx_desc_size;
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index c1546b916e4e..02cbf850bd85 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -2664,6 +2664,7 @@ static const struct ravb_hw_info ravb_gen3_hw_info = {
>  	.net_features = NETIF_F_RXCSUM,
>  	.stats_len = ARRAY_SIZE(ravb_gstrings_stats),
>  	.tccr_mask = TCCR_TSRQ0 | TCCR_TSRQ1 | TCCR_TSRQ2 | TCCR_TSRQ3,
> +	.tx_max_frame_size = SZ_2K,
>  	.rx_max_frame_size = SZ_2K,
>  	.rx_buffer_size = SZ_2K +
>  			  SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
> @@ -2689,6 +2690,7 @@ static const struct ravb_hw_info ravb_gen2_hw_info = {
>  	.net_features = NETIF_F_RXCSUM,
>  	.stats_len = ARRAY_SIZE(ravb_gstrings_stats),
>  	.tccr_mask = TCCR_TSRQ0 | TCCR_TSRQ1 | TCCR_TSRQ2 | TCCR_TSRQ3,
> +	.tx_max_frame_size = SZ_2K,
>  	.rx_max_frame_size = SZ_2K,
>  	.rx_buffer_size = SZ_2K +
>  			  SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
> @@ -2711,6 +2713,7 @@ static const struct ravb_hw_info ravb_rzv2m_hw_info = {
>  	.net_features = NETIF_F_RXCSUM,
>  	.stats_len = ARRAY_SIZE(ravb_gstrings_stats),
>  	.tccr_mask = TCCR_TSRQ0 | TCCR_TSRQ1 | TCCR_TSRQ2 | TCCR_TSRQ3,
> +	.tx_max_frame_size = SZ_2K,
>  	.rx_max_frame_size = SZ_2K,
>  	.rx_buffer_size = SZ_2K +
>  			  SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
> @@ -2735,6 +2738,7 @@ static const struct ravb_hw_info gbeth_hw_info = {
>  	.net_features = NETIF_F_RXCSUM | NETIF_F_HW_CSUM,
>  	.stats_len = ARRAY_SIZE(ravb_gstrings_stats_gbeth),
>  	.tccr_mask = TCCR_TSRQ0,
> +	.tx_max_frame_size = 1522,
>  	.rx_max_frame_size = SZ_8K,
>  	.rx_buffer_size = SZ_2K,
>  	.rx_desc_size = sizeof(struct ravb_rx_desc),
> @@ -2946,7 +2950,7 @@ static int ravb_probe(struct platform_device *pdev)
>  	priv->avb_link_active_low =
>  		of_property_read_bool(np, "renesas,ether-link-active-low");
>  
> -	ndev->max_mtu = info->rx_max_frame_size -
> +	ndev->max_mtu = info->tx_max_frame_size -
>  		(ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN);
>  	ndev->min_mtu = ETH_MIN_MTU;
>  
> -- 
> 2.39.2
> 

-- 
Kind Regards,
Niklas Söderlund