From 30ebad2dee1bc348c9b8234f0649a0b8f7a9cb40 Mon Sep 17 00:00:00 2001
From: Gabor Juhos <juhosg@openwrt.org>
Date: Sat, 11 Jan 2014 11:15:30 +0000
Subject: [PATCH] ar71xx: ag71xx: increase calculated max frame length value
The r39147 commit introduces a regression: at lease on some routers
with ar8216 switch large packets get lost if 802.1q tagged port is
used on the interface connected to the aforementioned switch.
The r39147 changes code in the way so interface is set to accept
packets no longer than max ethernet frame length for a given mtu.
Unfortunately ar8216 has a feature: it sends two additional bytes
as a packet header and those this header needs to be added to the
max frame length. Otherwise long enough packets get lost.
The problem only manuifests itself if interface is used in vlan
tagged mode. If interface is untagged then ar8216's header fits
into space used by 802.1q tag and not packets are lost.
Include two additional bytes in the max frame length calculation
to fix the issue.
This patch is tested and works with Trendnet TEW-632BRP.
Signed-off-by Nikolay Martynov <mar.kolya@gmail.com>
Patchwork: http://patchwork.openwrt.org/patch/4656/
[juhosg:
- simplify the patch to include the additional bytes of the
switch header unconditionally,
- change subject and update commit message]
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
SVN-Revision: 39219
---
.../files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
index 715c1cef1b..d010373155 100644
--- a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
+++ b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
@@ -28,9 +28,11 @@ static int ag71xx_msg_level = -1;
module_param_named(msg_level, ag71xx_msg_level, int, 0);
MODULE_PARM_DESC(msg_level, "Message level (-1=defaults,0=none,...,16=all)");
+#define ETH_SWITCH_HEADER_LEN 2
+
static inline unsigned int ag71xx_max_frame_len(unsigned int mtu)
{
- return ETH_HLEN + VLAN_HLEN + mtu + ETH_FCS_LEN;
+ return ETH_SWITCH_HEADER_LEN + ETH_HLEN + VLAN_HLEN + mtu + ETH_FCS_LEN;
}
static void ag71xx_dump_dma_regs(struct ag71xx *ag)
--
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