Commit 39eddb4c authored Jan 18, 2009 by Richard Röjfors Committed by David S. Miller Jan 19, 2009

macb: avoid lockup when TGO during underrun



In rare cases when an underrun occur, all macb buffers where consumed
and the netif_queue was stopped infinitely. This happens then the TGO
(transfer ongoing) bit in the TSR is set (and UND). It seems like
clening up after the underrun makes the driver and the macb hardware
end up in an inconsistent state. The result of this is that in the
following calls to macb_tx no TX buffers are released -> the
netif_queue was stopped, and never woken up again.

The solution is to disable the transmitter, if TGO is set, before
clening up after the underrun, and re-enable the transmitter when the
cleaning up is done.

Signed-off-by: Richard Röjfors <richard.rojfors@endian.se>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 24e94de4

drivers/net/macb.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -321,6 +321,10 @@ static void macb_tx(struct macb *bp)
		printk(KERN_ERR "%s: TX underrun, resetting buffers\n",
		bp->dev->name);

		/* Transfer ongoing, disable transmitter, to avoid confusion */
		if (status & MACB_BIT(TGO))
		macb_writel(bp, NCR, macb_readl(bp, NCR) & ~MACB_BIT(TE));

		head = bp->tx_head;

		/Mark all the buffer as used to avoid sending a lost buffer/
		@@ -343,6 +347,10 @@ static void macb_tx(struct macb *bp)
		}

		bp->tx_head = bp->tx_tail = 0;

		/* Enable the transmitter again */
		if (status & MACB_BIT(TGO))
		macb_writel(bp, NCR, macb_readl(bp, NCR) \| MACB_BIT(TE));
		}

		if (!(status & MACB_BIT(COMP)))

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