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8139too: move wmb before TX DMA start
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The write barrier should be used before starting a DMA transfer. This fixes
a problem, where almost all packets received on another machine had garbled
content. Tested with an RTL8100C on a MIPS machine.

Signed-off-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Andreas Oberritter authored and David S. Miller committed Oct 9, 2008
1 parent ed4cb13 commit 176eaa5
Showing 1 changed file with 6 additions and 1 deletion.
7 changes: 6 additions & 1 deletion drivers/net/8139too.c
Original file line number Diff line number Diff line change
Expand Up @@ -1723,13 +1723,18 @@ static int rtl8139_start_xmit (struct sk_buff *skb, struct net_device *dev)
}

spin_lock_irqsave(&tp->lock, flags);
/*
* Writing to TxStatus triggers a DMA transfer of the data
* copied to tp->tx_buf[entry] above. Use a memory barrier
* to make sure that the device sees the updated data.
*/
wmb();
RTL_W32_F (TxStatus0 + (entry * sizeof (u32)),
tp->tx_flag | max(len, (unsigned int)ETH_ZLEN));

dev->trans_start = jiffies;

tp->cur_tx++;
wmb();

if ((tp->cur_tx - NUM_TX_DESC) == tp->dirty_tx)
netif_stop_queue (dev);
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