-----Original Message-----
From: Yu, DapengX <redacted>
Sent: Friday, February 19, 2021 6:03 PM
To: Guo, Jia <redacted>; Wang, Haiyue <redacted>
Cc: dev@dpdk.org; Yu, DapengX <redacted>; stable@dpdk.org
Subject: [PATCH] net/e1000: remove MTU setting limitation

From: Dapeng Yu <redacted>

Currently, if requested MTU is bigger than mbuf size and scattered receive is
not enabled, setting MTU to that value fails.

This patch allows setting this special MTU when device is stopped, because
scattered_rx will be re-configured during next port start and driver may
enable scattered receive according new MTU value.

After this patch, driver may select different receive function automatically
after MTU set, according MTU values selected.

Fixes: 59d0ecdbf0e1 ("ethdev: MTU accessors")
Cc: stable@dpdk.org

Signed-off-by: Dapeng Yu <redacted>
---
 drivers/net/e1000/em_ethdev.c  | 12 ++++++++----
drivers/net/e1000/igb_ethdev.c | 12 ++++++++----
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/net/e1000/em_ethdev.c

b/drivers/net/e1000/em_ethdev.c index 9b8c4a7de..3c6f643c1 100644

--- a/drivers/net/e1000/em_ethdev.c
+++ b/drivers/net/e1000/em_ethdev.c

@@ -1805,11 +1805,15 @@ eth_em_mtu_set(struct rte_eth_dev *dev,

uint16_t mtu)
 	if (mtu < RTE_ETHER_MIN_MTU || frame_size >
dev_info.max_rx_pktlen)
 		return -EINVAL;

-	/* refuse mtu that requires the support of scattered packets when
this
-	 * feature has not been enabled before. */
-	if (!dev->data->scattered_rx &&
-	    frame_size > dev->data->min_rx_buf_size -
RTE_PKTMBUF_HEADROOM)
+	/*
+	 * If device is started, refuse mtu that requires the support of
+	 * scattered packets when this feature has not been enabled before.
+	 */
+	if (dev->data->dev_started && !dev->data->scattered_rx &&
+	    frame_size > dev->data->min_rx_buf_size -
RTE_PKTMBUF_HEADROOM) {
+		PMD_INIT_LOG(ERR, "Stop port first.");
 		return -EINVAL;
+	}

 	hw = E1000_DEV_PRIVATE_TO_HW(dev->data->dev_private);
 	rctl = E1000_READ_REG(hw, E1000_RCTL); diff --git
a/drivers/net/e1000/igb_ethdev.c b/drivers/net/e1000/igb_ethdev.c index
5323504e9..1716d6b90 100644

--- a/drivers/net/e1000/igb_ethdev.c
+++ b/drivers/net/e1000/igb_ethdev.c

@@ -4394,11 +4394,15 @@ eth_igb_mtu_set(struct rte_eth_dev *dev,

uint16_t mtu)
 			frame_size > dev_info.max_rx_pktlen)
 		return -EINVAL;

-	/* refuse mtu that requires the support of scattered packets when
this
-	 * feature has not been enabled before. */
-	if (!dev->data->scattered_rx &&
-	    frame_size > dev->data->min_rx_buf_size -
RTE_PKTMBUF_HEADROOM)
+	/*
+	 * If device is started, refuse mtu that requires the support of
+	 * scattered packets when this feature has not been enabled before.
+	 */
+	if (dev->data->dev_started && !dev->data->scattered_rx &&
+	    frame_size > dev->data->min_rx_buf_size -
RTE_PKTMBUF_HEADROOM) {
+		PMD_INIT_LOG(ERR, "Stop port first.");
 		return -EINVAL;
+	}

 	rctl = E1000_READ_REG(hw, E1000_RCTL);

--
2.27.0