From: John Feeney <jfeeney@redhat.com>
Date: Thu, 9 Dec 2010 00:11:08 -0500
Subject: [net] tg3: increase jumbo flag threshold
Message-id: <4D001E9C.8010206@redhat.com>
Patchwork-id: 30021
O-Subject: [RHEL5.6 PATCH] tg3: Increase jumbo flag threshold
Bugzilla: 660506
RH-Acked-by: David S. Miller <davem@redhat.com>
RH-Acked-by: Jiri Pirko <jpirko@redhat.com>
RH-Acked-by: Stefan Assmann <sassmann@redhat.com>

bz660506
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=660506
tg3: Increase tx jumbo bd flag threshold

Description of problem:
According to Broadcom, setting the jumbo BD flag too soon seems to
cause some tx recovery problems on 5719.

Solution:
Increase the jumbo flag threshold from 1500 to 1518.

Upstream commits:
The tg3 maintainer (Matt Carlson from Broadcom) has posted
this patch to netdev. I have included a copy of that here:

>The current transmit routines set the jumbo frame BD flag too
>aggressively.  This can reduce performance for common cases.  This patch
>raises the jumbo flag threshold to 1518, up from 1500.
>
>Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
>Reviewed-by: Benjamin Li <benli@broadcom.com>
>---
> drivers/net/tg3.c |    4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
>index afb79db..b8ae5e1 100644
>--- a/drivers/net/tg3.c
>+++ b/drivers/net/tg3.c
>@@ -5761,7 +5761,7 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb,
> 	dma_unmap_addr_set(&tnapi->tx_buffers[entry], mapping, mapping);
>
> 	if ((tp->tg3_flags3 & TG3_FLG3_USE_JUMBO_BDFLAG) &&
>-	    !mss && skb->len > ETH_DATA_LEN)
>+	    !mss && skb->len > VLAN_ETH_FRAME_LEN)
> 		base_flags |= TXD_FLAG_JMB_PKT;
>
> 	tg3_set_txd(tnapi, entry, mapping, len, base_flags,
>@@ -5995,7 +5995,7 @@ static netdev_tx_t tg3_start_xmit_dma_bug(struct sk_buff *skb,
> #endif
>
> 	if ((tp->tg3_flags3 & TG3_FLG3_USE_JUMBO_BDFLAG) &&
>-	    !mss && skb->len > ETH_DATA_LEN)
>+	    !mss && skb->len > VLAN_ETH_FRAME_LEN)
> 		base_flags |= TXD_FLAG_JMB_PKT;
>
> 	len = skb_headlen(skb);
>-- 1.7.2.2 "

Note:
When applying the patch it was noticed that there is a bug in
the RHEL5.6 tg3 driver. The if condition to set the value of
base_flags to TXD_FLAG_JMB_PKT was found in tg3_start_xmit_dma_bug()
twice, instead of being found in tg3_start_xmit() and
tg3_start_xmit_dma_bug(). This caused the setting of TXD_FLAG_JMB_PKT
to be set again superfluously and not be set at all in tg3_start_xmit().

This patch fixes that problem, in addition to increasing the threshold.

Brew:
Successfully built in Brew for all architectures.

Testing:
Broadcom is testing the rpm with this patch and I will provide
an update upon arrival.

In addition, I performed some level of sanity testing
on a tg3 nic but not with a 5719 because we don't have
one in Beaker.

Acks would be appreciated. Thanks.

Signed-off-by: Jarod Wilson <jarod@redhat.com>

diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index 29f7d70..479dab5 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -5197,6 +5197,10 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	tnapi->tx_buffers[entry].skb = skb;
 	pci_unmap_addr_set(&tnapi->tx_buffers[entry], mapping, mapping);
 
+	if ((tp->tg3_flags3 & TG3_FLG3_USE_JUMBO_BDFLAG) &&
+	    !mss && skb->len > VLAN_ETH_FRAME_LEN)
+		base_flags |= TXD_FLAG_JMB_PKT;
+
 	tg3_set_txd(tnapi, entry, mapping, len, base_flags,
 		    (skb_shinfo(skb)->nr_frags == 0) | (mss << 1));
 
@@ -5390,7 +5394,7 @@ static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev)
 #endif
 
 	if ((tp->tg3_flags3 & TG3_FLG3_USE_JUMBO_BDFLAG) &&
-	    !mss && skb->len > ETH_DATA_LEN)
+	    !mss && skb->len > VLAN_ETH_FRAME_LEN)
 		base_flags |= TXD_FLAG_JMB_PKT;
 
 	/* Queue skb data, a.k.a. the main skb fragment. */
@@ -5415,10 +5419,6 @@ static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev)
 	if (tp->tg3_flags3 & TG3_FLG3_5701_DMA_BUG)
 		would_hit_hwbug = 1;
 
-	if ((tp->tg3_flags3 & TG3_FLG3_USE_JUMBO_BDFLAG) &&
-	    !mss && skb->len > ETH_DATA_LEN)
-		base_flags |= TXD_FLAG_JMB_PKT;
-
 	tg3_set_txd(tnapi, entry, mapping, len, base_flags,
 		    (skb_shinfo(skb)->nr_frags == 0) | (mss << 1));