[patch 4/5] r8169: reduce max MTU for large frames

[Francois Romieu <romieu@xxxxxxxxxxxxx>]

The device does not support the whole mtu range it claims. Experimenting
with the Tx threshold and/or the PCI burst size does not seem to improve
the behavior.

Signed-off-by: Francois Romieu <romieu@xxxxxxxxxxxxx>

diff -puN drivers/net/r8169.c~r8169-265 drivers/net/r8169.c
--- linux-2.6.10-rc2/drivers/net/r8169.c~r8169-265      2004-12-05 
22:36:25.000000000 +0100
+++ linux-2.6.10-rc2-fr/drivers/net/r8169.c     2004-12-07 00:54:48.313082500 
+0100
@@ -112,7 +112,8 @@ static int multicast_filter_limit = 32;
 #define RX_DMA_BURST   6       /* Maximum PCI burst, '6' is 1024 */
 #define TX_DMA_BURST   6       /* Maximum PCI burst, '6' is 1024 */
 #define EarlyTxThld    0x3F    /* 0x3F means NO early transmit */
-#define RxPacketMaxSize        0x3FE8  /* 16K - 1 - ETH_HLEN - VLAN - CRC */
+#define RxPacketMaxSize        0x3FE8  /* 16K - 1 - ETH_HLEN - VLAN - CRC... */
+#define SafeMtu                0x1c20  /* ... actually life sucks beyond ~7k */
 #define InterFrameGap  0x03    /* 3 means InterFrameGap = the shortest one */
 
 #define R8169_REGS_SIZE                256
@@ -1592,9 +1593,9 @@ static int rtl8169_change_mtu(struct net
        struct rtl8169_private *tp = netdev_priv(dev);
        int ret = 0;
 
-       if (new_mtu < ETH_ZLEN || new_mtu > RxPacketMaxSize)
+       if (new_mtu < ETH_ZLEN || new_mtu > SafeMtu)
                return -EINVAL;
-       
+
        dev->mtu = new_mtu;
 
        if (!netif_running(dev)) 

_