mvpp2: refactor the HW checksum setup

The hardware can only offload checksum calculation on first port due to
the Tx FIFO size limitation, and has a maximum L3 offset of 128 bytes.
Document this in a comment and move duplicated code in a function.

Fixes: 576193f2d579 ("net: mvpp2: jumbo frames support")
Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index 68fa2d5..e2e61a4 100644 (file)
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -811,6 +811,26 @@ static int mvpp2_swf_bm_pool_init(struct mvpp2_port *port)
        return 0;
 }
 
+static void mvpp2_set_hw_csum(struct mvpp2_port *port,
+                             enum mvpp2_bm_pool_log_num new_long_pool)
+{
+       const netdev_features_t csums = NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
+
+       /* Update L4 checksum when jumbo enable/disable on port.
+        * Only port 0 supports hardware checksum offload due to
+        * the Tx FIFO size limitation.
+        * Also, don't set NETIF_F_HW_CSUM because L3_offset in TX descriptor
+        * has 7 bits, so the maximum L3 offset is 128.
+        */
+       if (new_long_pool == MVPP2_BM_JUMBO && port->id != 0) {
+               port->dev->features &= ~csums;
+               port->dev->hw_features &= ~csums;
+       } else {
+               port->dev->features |= csums;
+               port->dev->hw_features |= csums;
+       }
+}
+
 static int mvpp2_bm_update_mtu(struct net_device *dev, int mtu)
 {
        struct mvpp2_port *port = netdev_priv(dev);
@@ -843,15 +863,7 @@ static int mvpp2_bm_update_mtu(struct net_device *dev, int mtu)
                /* Add port to new short & long pool */
                mvpp2_swf_bm_pool_init(port);
 
-               /* Update L4 checksum when jumbo enable/disable on port */
-               if (new_long_pool == MVPP2_BM_JUMBO && port->id != 0) {
-                       dev->features &= ~(NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM);
-                       dev->hw_features &= ~(NETIF_F_IP_CSUM |
-                                             NETIF_F_IPV6_CSUM);
-               } else {
-                       dev->features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
-                       dev->hw_features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
-               }
+               mvpp2_set_hw_csum(port, new_long_pool);
        }
 
        dev->mtu = mtu;
@@ -5193,10 +5205,7 @@ static int mvpp2_port_probe(struct platform_device *pdev,
                dev->features |= NETIF_F_NTUPLE;
        }
 
-       if (port->pool_long->id == MVPP2_BM_JUMBO && port->id != 0) {
-               dev->features &= ~(NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM);
-               dev->hw_features &= ~(NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM);
-       }
+       mvpp2_set_hw_csum(port, port->pool_long->id);
 
        dev->vlan_features |= features;
        dev->gso_max_segs = MVPP2_MAX_TSO_SEGS;