Commit d78ae2dc authored Aug 26, 2007 by Francois Romieu Committed by Francois Romieu Sep 19, 2007

r8169: workaround against ignored TxPoll writes (8168)

The 8168 ignores the requests to fetch the Tx descriptors when
the relevant TxPoll bit is already set. It easily kills the
performances of the 8168. David Gundersen has noticed that it
is enough to wait for the completion of the DMA transfer (NPQ
bit is cleared) before writing the TxPoll register again.

The extra IO traffic added by the proposed workaround could be
minimalized but it is not a high-priority task.

Fix for:
http://bugzilla.kernel.org/show_bug.cgi?id=7924
http://bugzilla.kernel.org/show_bug.cgi?id=8688
(http://bugzilla.kernel.org/show_bug.cgi?id=7555

 ?)

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Cc: David Gundersen <gundy@iinet.net.au>
Cc: Edward Hsu <edward_hsu@realtek.com.tw>

parent 65d916d9

drivers/net/r8169.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -2570,6 +2570,15 @@ static void rtl8169_tx_interrupt(struct net_device *dev,
		(TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)) {
		netif_wake_queue(dev);
		}
		/*
		* 8168 hack: TxPoll requests are lost when the Tx packets are
		* too close. Let's kick an extra TxPoll request when a burst
		* of start_xmit activity is detected (if it is not detected,
		* it is slow enough). -- FR
		*/
		smp_rmb();
		if (tp->cur_tx != dirty_tx)
		RTL_W8(TxPoll, NPQ);
		}
		}

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