Re: [PATCH v3] net/nfp: fix mtu settings

[Ferruh Yigit <ferruh.yigit@xilinx.com>]

On 3/30/2022 4:17 AM, Peng Zhang wrote:
> 1.When the setting mtu is higher than flbufsz, the mtu doesn't work.
> But it doesn't have any notice about this restrict.
> 2.add the min_mtu and max_mtu in the nfp_net_infos_get() to avoid
> the setting mtu isn't in the range
> 
> This patch will add these restrict of nfp mtu.
> 

+Niklas, as he is the maintainer of the PMD.

Can you please prefer uppercase 'MTU' in title/commit log and error log?

I assume scattered_rx is not supported by the device, which enables 
receiving packets bigger than mbuf data size.

> Fixes: d4a27a3b092a ("nfp: add basic features")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Peng Zhang <peng.zhang@corigine.com>
> Signed-off-by: Chaoyong He <chaoyong.he@corigine.com>
> Signed-off-by: Louis Peens <louis.peens@corigine.com>
> ---
> v3:
> * git summary
> 
> v2:
> * add the min_mtu and max_mtu in the nfp_net_infos_get()
> ---
> 
>   drivers/net/nfp/nfp_common.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/net/nfp/nfp_common.c b/drivers/net/nfp/nfp_common.c
> index f8978e803a..4e48e33a63 100644
> --- a/drivers/net/nfp/nfp_common.c
> +++ b/drivers/net/nfp/nfp_common.c
> @@ -693,6 +693,8 @@ nfp_net_infos_get(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info)
>   
>   	hw = NFP_NET_DEV_PRIVATE_TO_HW(dev->data->dev_private);
>   
> +	dev_info->max_mtu = (uint16_t)hw->max_mtu;
> +	dev_info->min_mtu = RTE_ETHER_MIN_MTU;
>   	dev_info->max_rx_queues = (uint16_t)hw->max_rx_queues;
>   	dev_info->max_tx_queues = (uint16_t)hw->max_tx_queues;
>   	dev_info->min_rx_bufsize = RTE_ETHER_MIN_MTU;
> @@ -956,6 +958,13 @@ nfp_net_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
>   		return -EBUSY;
>   	}
>   
> +	/* the setting mtu is lower than flbufsz */
> +	if (mtu > hw->flbufsz) {
> +		PMD_DRV_LOG(ERR, "the setting mtu must be lower than current mbufsize of %d",

You may want to start log with uppercase as done in other logs, for 
consistency.
Also may want to print the MTU value in the log.

> +			    hw->flbufsz);
> +		return -ERANGE;
> +	}

Should this be checked in 'nfb_eth_dev_configure()' too, where 
'dev->data->mtu' can be set?

> +
>   	/* writing to configuration space */
>   	nn_cfg_writel(hw, NFP_NET_CFG_MTU, mtu);
>