[PATCH v2 5/6] net/nfb: support setting Rx MTU

spinler
2026-02-17T11:03:59Z

Enable configuration of the MTU on the Rx MAC assigned to the port.
The max MTU value is also reported in dev_info.

Signed-off-by: Martin Spinler <spinler@cesnet.cz>
---
doc/guides/rel_notes/release_26_03.rst | 4 +--
drivers/net/nfb/nfb.h | 1 +
drivers/net/nfb/nfb_ethdev.c | 45 +++++++++++++++++++++++++-
3 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/doc/guides/rel_notes/release_26_03.rst b/doc/guides/rel_notes/release_26_03.rst
index ac76ac5b67..7ce852e349 100644
--- a/doc/guides/rel_notes/release_26_03.rst
+++ b/doc/guides/rel_notes/release_26_03.rst
@@ -64,10 +64,10 @@ New Features
* The timestamp value has been updated to make it usable.
* The DPDK port now represents just one Ethernet port instead of all Ethernet ports on the NIC.
* All ports are used by default, but a subset can be selected using the ``port`` argument.
- * Report firmware version and correct Ethernet link speed.
+ * Report firmware version, correct Ethernet link speed and maximum capable MTU value.
* Common CESNET-NDK-based adapters have been added,
including the FB2CGHH (Silicom Denmark) and XpressSX AGI-FH400G (Reflex CES).
- * Added support for configuration of the RS-FEC mode, Link Up / Link Down state.
+ * Added support for configuration of the RS-FEC mode, Link Up / Link Down state, and the Rx MTU.

Removed Items
diff --git a/drivers/net/nfb/nfb.h b/drivers/net/nfb/nfb.h
index 3b905bbb3b..7d192946bc 100644
--- a/drivers/net/nfb/nfb.h
+++ b/drivers/net/nfb/nfb.h
@@ -84,6 +84,7 @@ struct pmd_priv {
int *queue_map_rx;
/** Mapping from DPDK TX queue index to firmware queue ID */
int *queue_map_tx;
+ uint16_t frame_len_max_cap; /**< Maximum length obtained from Rx MAC */
bool ready; /**< This structure is initialized for usage in secondary process */
};

diff --git a/drivers/net/nfb/nfb_ethdev.c b/drivers/net/nfb/nfb_ethdev.c
index a556ceca67..1093c6edf4 100644
--- a/drivers/net/nfb/nfb_ethdev.c
+++ b/drivers/net/nfb/nfb_ethdev.c
@@ -51,6 +51,7 @@ static struct nfb_pmd_internals_head nfb_eth_dev_list =
TAILQ_HEAD_INITIALIZER(nfb_eth_dev_list);

static int nfb_eth_dev_uninit(struct rte_eth_dev *dev);
+static int nfb_eth_mtu_set(struct rte_eth_dev *dev, uint16_t mtu);

static int
nfb_mdio_read(void *priv, int prtad, int devad, uint16_t addr)
@@ -271,6 +272,10 @@ nfb_eth_dev_configure(struct rte_eth_dev *dev __rte_unused)
int ret;
struct rte_eth_conf *dev_conf = &dev->data->dev_conf;

+ ret = nfb_eth_mtu_set(dev, dev_conf->rxmode.mtu);
+ if (ret)
+ goto err_mtu_set;
+
if (dev_conf->rxmode.offloads & RTE_ETH_RX_OFFLOAD_TIMESTAMP) {
ret = rte_mbuf_dyn_rx_timestamp_register
(&nfb_timestamp_dynfield_offset,
@@ -285,6 +290,7 @@ nfb_eth_dev_configure(struct rte_eth_dev *dev __rte_unused)
return 0;

err_ts_register:
+err_mtu_set:
nfb_eth_dev_uninit(dev);
return ret;
}
@@ -330,7 +336,8 @@ nfb_eth_dev_info(struct rte_eth_dev *dev,

dev_info->max_mac_addrs = nfb_eth_get_max_mac_address_count(dev);

- dev_info->max_rx_pktlen = (uint32_t)-1;
+ dev_info->max_rx_pktlen = priv->frame_len_max_cap;
+ dev_info->max_mtu = dev_info->max_rx_pktlen - (RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN);
dev_info->max_rx_queues = priv->max_rx_queues;
dev_info->max_tx_queues = priv->max_tx_queues;
dev_info->speed_capa = RTE_ETH_LINK_SPEED_FIXED;
@@ -575,6 +582,39 @@ nfb_eth_mac_addr_remove(struct rte_eth_dev *dev, uint32_t index)
nc_rxmac_set_mac(internals->rxmac[i], index, 0, 0);
}

+static uint16_t
+nfb_mac_read_frame_len_max_cap(struct pmd_internals *intl)
+{
+ unsigned int i;
+ uint16_t ret = UINT16_MAX;
+ struct nc_rxmac_status status;
+
+ for (i = 0; i < intl->max_rxmac; ++i) {
+ status.frame_length_max_capable = 0;
+ nc_rxmac_read_status(intl->rxmac[i], &status);
+ if (status.frame_length_max_capable && ret > status.frame_length_max_capable)
+ ret = status.frame_length_max_capable;
+ }
+ return ret;
+}
+
+static int
+nfb_eth_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
+{
+ unsigned int i;
+ struct pmd_internals *intl = dev->process_private;
+ struct pmd_priv *priv = dev->data->dev_private;
+
+ mtu += RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN;
+ if (mtu > priv->frame_len_max_cap || mtu < RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN)
+ return -EINVAL;
+
+ for (i = 0; i < intl->max_rxmac; ++i)
+ nc_rxmac_set_frame_length(intl->rxmac[i], mtu, RXMAC_FRAME_LENGTH_MAX);
+
+ return 0;
+}
+
static int
nfb_eth_fw_version_get(struct rte_eth_dev *dev, char *fw_version,
size_t fw_size)
@@ -690,6 +730,7 @@ static const struct eth_dev_ops ops = {
.mac_addr_set = nfb_eth_mac_addr_set,
.mac_addr_add = nfb_eth_mac_addr_add,
.mac_addr_remove = nfb_eth_mac_addr_remove,
+ .mtu_set = nfb_eth_mtu_set,
.fw_version_get = nfb_eth_fw_version_get,
.fec_get = nfb_eth_fec_get,
.fec_set = nfb_eth_fec_set,
@@ -793,6 +834,8 @@ nfb_eth_dev_init(struct rte_eth_dev *dev, void *init_data)
}
}

+ priv->frame_len_max_cap = nfb_mac_read_frame_len_max_cap(internals);
+
/* Allocate space for MAC addresses */
mac_count = nfb_eth_get_max_mac_address_count(dev);
data->mac_addrs = rte_zmalloc(data->name,
--
2.53.0