From d78ae2dcc2acebb9a1048278f47f762c069db75c Mon Sep 17 00:00:00 2001 From: Francois Romieu Date: Sun, 26 Aug 2007 20:08:19 +0200 Subject: [PATCH] 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 Cc: David Gundersen Cc: Edward Hsu --- drivers/net/r8169.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c index d9bb51b..c921ec3 100644 --- a/drivers/net/r8169.c +++ b/drivers/net/r8169.c @@ -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); } } -- 1.8.2.3