net/e1000: remove MTU setting limitation

[ upstream commit 0984d19 ]

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: 59d0ecd ("ethdev: MTU accessors")

Signed-off-by: Dapeng Yu <dapengx.yu@intel.com>
Acked-by: Jeff Guo <jia.guo@intel.com>

drivers/net/e1000/em_ethdev.c

@@ -1801,11 +1801,15 @@ 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);

drivers/net/e1000/igb_ethdev.c

@@ -4568,11 +4568,15 @@ 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);