Subject: [PATCH 16/16] net: mvneta: disable IP checksum with jumbo frames for Armada 370

From: Simon Guinot <[email-masked]>
Date: Tue, 30 Jun 2015 16:20:22 +0200

[ Upstream commit b65657fc240ae6c1d2a1e62db9a0e61ac9631d7a ]

The Ethernet controller found in the Armada 370, 380 and 385 SoCs don't
support TCP/IP checksumming with frame sizes larger than 1600 bytes.

This patch fixes the issue by disabling the features NETIF_F_IP_CSUM and
NETIF_F_TSO for the Armada 370 and compatibles SoCs when the MTU is set
to a value greater than 1600 bytes.

Signed-off-by: Simon Guinot <[email-masked]>
Fixes: c5aff18204da ("net: mvneta: driver for Marvell Armada 370/XP network unit")
Cc: <[email-masked]> # v3.8+
Acked-by: Thomas Petazzoni <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/net/ethernet/marvell/mvneta.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index e62c951..fb34708 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -304,6 +304,7 @@ struct mvneta_port {
 	unsigned int link;
 	unsigned int duplex;
 	unsigned int speed;
+	unsigned int tx_csum_limit;
 };
 
 /* The mvneta_tx_desc and mvneta_rx_desc structures describe the
@@ -2441,8 +2442,10 @@ static int mvneta_change_mtu(struct net_device *dev, int mtu)
 
 	dev->mtu = mtu;
 
-	if (!netif_running(dev))
+	if (!netif_running(dev)) {
+		netdev_update_features(dev);
 		return 0;
+	}
 
 	/* The interface is running, so we have to force a
 	 * reallocation of the queues
@@ -2471,9 +2474,26 @@ static int mvneta_change_mtu(struct net_device *dev, int mtu)
 	mvneta_start_dev(pp);
 	mvneta_port_up(pp);
 
+	netdev_update_features(dev);
+
 	return 0;
 }
 
+static netdev_features_t mvneta_fix_features(struct net_device *dev,
+					     netdev_features_t features)
+{
+	struct mvneta_port *pp = netdev_priv(dev);
+
+	if (pp->tx_csum_limit && dev->mtu > pp->tx_csum_limit) {
+		features &= ~(NETIF_F_IP_CSUM | NETIF_F_TSO);
+		netdev_info(dev,
+			    "Disable IP checksum for MTU greater than %dB\n",
+			    pp->tx_csum_limit);
+	}
+
+	return features;
+}
+
 /* Get mac address */
 static void mvneta_get_mac_addr(struct mvneta_port *pp, unsigned char *addr)
 {
@@ -2791,6 +2811,7 @@ static const struct net_device_ops mvneta_netdev_ops = {
 	.ndo_set_rx_mode     = mvneta_set_rx_mode,
 	.ndo_set_mac_address = mvneta_set_mac_addr,
 	.ndo_change_mtu      = mvneta_change_mtu,
+	.ndo_fix_features    = mvneta_fix_features,
 	.ndo_get_stats64     = mvneta_get_stats64,
 	.ndo_do_ioctl        = mvneta_ioctl,
 };
@@ -3029,6 +3050,9 @@ static int mvneta_probe(struct platform_device *pdev)
 		}
 	}
 
+	if (of_device_is_compatible(dn, "marvell,armada-370-neta"))
+		pp->tx_csum_limit = 1600;
+
 	pp->tx_ring_size = MVNETA_MAX_TXD;
 	pp->rx_ring_size = MVNETA_MAX_RXD;
 
-- 
2.1.0