net/smsc911x.c: Set the VLAN1 register to fix VLAN MTU problem

The smsc911x driver would drop frames longer than 1518 bytes, which is a
problem for networks with VLAN tagging. The VLAN1 tag register is used
to increase the legal frame size to 1522 when a VLAN tag is identified.

Signed-off-by: Göran Weinholt <weinholt@csbnet.se>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/net/smsc911x.c b/drivers/net/smsc911x.c
index 64bfdae5956..d70bde95460 100644
--- a/drivers/net/smsc911x.c
+++ b/drivers/net/smsc911x.c
@@ -1178,6 +1178,11 @@ static int smsc911x_open(struct net_device *dev)
         smsc911x_reg_write(pdata, HW_CFG, 0x00050000);
         smsc911x_reg_write(pdata, AFC_CFG, 0x006E3740);
 
+        /* Increase the legal frame size of VLAN tagged frames to 1522 bytes */
+        spin_lock_irq(&pdata->mac_lock);
+        smsc911x_mac_write(pdata, VLAN1, ETH_P_8021Q);
+        spin_unlock_irq(&pdata->mac_lock);
+
         /* Make sure EEPROM has finished loading before setting GPIO_CFG */
         timeout = 50;
         while ((smsc911x_reg_read(pdata, E2P_CMD) & E2P_CMD_EPC_BUSY_) &&