8139too interframe gap

[DataCom - Abreu <abreu@xxxxxxxxxxxxxxxxxxxxxxxxx>]

Hi,

The driver 8139too configures interframe gap with the shortest possible 
interval. This behaviour was commited by Jeff on version 0.9.4.1. From 
changelog:

* Do not set Interfame Gap (IFG) bits in TxConfig

The chip spec, though, says that these bits must be set in order to 
conform to 802.3. There is a comment on the code that says exactly the 
opposite. I would like to know why the configuration is set this way.

I have a problem where an external device inserts VLAN tags in frames, 
thus reducing the gap more yet. After that, too close frames (except the
 
first one) are not recognized by a switch.

I have set these bits and my problem disappears. My patch follows:


--- linux-2.6.10/drivers/net/8139too.c  2004-12-24 19:33:47.000000000 -0200
+++ linux-2.6.10-mod/drivers/net/8139too.c      2005-02-03 13:47:15.000000000 
-0200
@@ -391,7 +391,7 @@
 /* Bits in TxConfig. */
 enum tx_config_bits {
        TxIFG1 = (1 << 25),     /* Interframe Gap Time */
-       TxIFG0 = (1 << 24),     /* Enabling these bits violates IEEE 802.3 */
+       TxIFG0 = (1 << 24),     /* Disabling any of these bits violates IEEE 
802.3 */
        TxLoopBack = (1 << 18) | (1 << 17), /* enable loopback test mode */
        TxCRC = (1 << 16),      /* DISABLE appending CRC to end of Tx packets */
        TxClearAbt = (1 << 0),  /* Clear abort (WO) */
@@ -723,7 +723,7 @@
 #endif
 
 static const unsigned int rtl8139_tx_config =
-       (TX_DMA_BURST << TxDMAShift) | (TX_RETRY << TxRetryShift);
+       TxIFG1 | TxIFG0 | (TX_DMA_BURST << TxDMAShift) | (TX_RETRY << 
TxRetryShift);
 
 static void __rtl8139_cleanup_dev (struct net_device *dev)
 {



Thanks.

Marcelo Abreu