[dpdk-dev] [PATCH 2/4] enic: set the max allowed MTU for the NIC

[John Daley <johndale@cisco.com>]

The max MTU is set to the max egress packet size allowed by the VIC
minus the size of a an IPv4 L2 header with .1Q (18 bytes).

Signed-off-by: John Daley <johndale@cisco.com>
---
 drivers/net/enic/enic.h        |  1 +
 drivers/net/enic/enic_ethdev.c |  3 ++-
 drivers/net/enic/enic_res.c    | 25 +++++++++++++++++--------
 drivers/net/enic/enic_res.h    |  4 +++-
 4 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/drivers/net/enic/enic.h b/drivers/net/enic/enic.h
index 1e6914e..78f7bd7 100644
--- a/drivers/net/enic/enic.h
+++ b/drivers/net/enic/enic.h
@@ -118,6 +118,7 @@ struct enic {
 	u8 ig_vlan_strip_en;
 	int link_status;
 	u8 hw_ip_checksum;
+	u16 max_mtu;
 
 	unsigned int flags;
 	unsigned int priv_flags;
diff --git a/drivers/net/enic/enic_ethdev.c b/drivers/net/enic/enic_ethdev.c
index 697ff82..31d9600 100644
--- a/drivers/net/enic/enic_ethdev.c
+++ b/drivers/net/enic/enic_ethdev.c
@@ -435,7 +435,8 @@ static void enicpmd_dev_info_get(struct rte_eth_dev *eth_dev,
 	device_info->max_rx_queues = enic->rq_count;
 	device_info->max_tx_queues = enic->wq_count;
 	device_info->min_rx_bufsize = ENIC_MIN_MTU;
-	device_info->max_rx_pktlen = enic->config.mtu;
+	device_info->max_rx_pktlen = enic->rte_dev->data->mtu
+				   + ETHER_HDR_LEN + 4;
 	device_info->max_mac_addrs = 1;
 	device_info->rx_offload_capa =
 		DEV_RX_OFFLOAD_VLAN_STRIP |
diff --git a/drivers/net/enic/enic_res.c b/drivers/net/enic/enic_res.c
index ebe379d..e82181f 100644
--- a/drivers/net/enic/enic_res.c
+++ b/drivers/net/enic/enic_res.c
@@ -83,6 +83,20 @@ int enic_get_vnic_config(struct enic *enic)
 	GET_CONFIG(intr_timer_usec);
 	GET_CONFIG(loop_tag);
 	GET_CONFIG(num_arfs);
+	GET_CONFIG(max_pkt_size);
+
+	/* max packet size is only defined in newer VIC firmware
+	 * and will be 0 for legacy firmware and VICs
+	 */
+	if (c->max_pkt_size > ENIC_DEFAULT_MAX_PKT_SIZE)
+		enic->max_mtu = c->max_pkt_size - (ETHER_HDR_LEN + 4);
+	else
+		enic->max_mtu = ENIC_DEFAULT_MAX_PKT_SIZE - (ETHER_HDR_LEN + 4);
+	if (c->mtu == 0)
+		c->mtu = 1500;
+
+	enic->rte_dev->data->mtu = min_t(u16, enic->max_mtu,
+					 max_t(u16, ENIC_MIN_MTU, c->mtu));
 
 	c->wq_desc_count =
 		min_t(u32, ENIC_MAX_WQ_DESCS,
@@ -96,21 +110,16 @@ int enic_get_vnic_config(struct enic *enic)
 		c->rq_desc_count));
 	c->rq_desc_count &= 0xffffffe0; /* must be aligned to groups of 32 */
 
-	if (c->mtu == 0)
-		c->mtu = 1500;
-	c->mtu = min_t(u16, ENIC_MAX_MTU,
-		max_t(u16, ENIC_MIN_MTU,
-		c->mtu));
-
 	c->intr_timer_usec = min_t(u32, c->intr_timer_usec,
 		vnic_dev_get_intr_coal_timer_max(enic->vdev));
 
 	dev_info(enic_get_dev(enic),
 		"vNIC MAC addr %02x:%02x:%02x:%02x:%02x:%02x "
-		"wq/rq %d/%d mtu %d\n",
+		"wq/rq %d/%d mtu %d, max mtu:%d\n",
 		enic->mac_addr[0], enic->mac_addr[1], enic->mac_addr[2],
 		enic->mac_addr[3], enic->mac_addr[4], enic->mac_addr[5],
-		c->wq_desc_count, c->rq_desc_count, c->mtu);
+		c->wq_desc_count, c->rq_desc_count,
+		enic->rte_dev->data->mtu, enic->max_mtu);
 	dev_info(enic_get_dev(enic), "vNIC csum tx/rx %s/%s "
 		"rss %s intr mode %s type %s timer %d usec "
 		"loopback tag 0x%04x\n",
diff --git a/drivers/net/enic/enic_res.h b/drivers/net/enic/enic_res.h
index 3c8e303..303530e 100644
--- a/drivers/net/enic/enic_res.h
+++ b/drivers/net/enic/enic_res.h
@@ -46,7 +46,9 @@
 #define ENIC_MAX_RQ_DESCS		4096
 
 #define ENIC_MIN_MTU			68
-#define ENIC_MAX_MTU			9000
+
+/* Does not include (possible) inserted VLAN tag and FCS */
+#define ENIC_DEFAULT_MAX_PKT_SIZE	9022
 
 #define ENIC_MULTICAST_PERFECT_FILTERS	32
 #define ENIC_UNICAST_PERFECT_FILTERS	32
-- 
2.7.0