8139too interframe gap
From: DataCom - Abreu <hidden>
Date: 2005-02-03 16:51:10
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