[PATCH 5.14 414/432] net: dsa: lantiq_gswip: fix maximum frame length

Greg Kroah-Hartman
2021-09-16T17:51:58Z

From: Jan Hoffmann <jan@3e8.eu>

commit 552799f8b3b0074d2617f53a63a088f9514a66e3 upstream.

Currently, outgoing packets larger than 1496 bytes are dropped when
tagged VLAN is used on a switch port.

Add the frame check sequence length to the value of the register
GSWIP_MAC_FLEN to fix this. This matches the lantiq_ppa vendor driver,
which uses a value consisting of 1518 bytes for the MAC frame, plus the
lengths of special tag and VLAN tags.

Fixes: 14fceff4771e ("net: dsa: Add Lantiq / Intel DSA driver for vrx200")
Cc: stable@vger.kernel.org
Signed-off-by: Jan Hoffmann <jan@3e8.eu>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/dsa/lantiq_gswip.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/dsa/lantiq_gswip.c
+++ b/drivers/net/dsa/lantiq_gswip.c
@@ -843,7 +843,8 @@ static int gswip_setup(struct dsa_switch

gswip_switch_mask(priv, 0, GSWIP_MAC_CTRL_2_MLEN,
GSWIP_MAC_CTRL_2p(cpu_port));
- gswip_switch_w(priv, VLAN_ETH_FRAME_LEN + 8, GSWIP_MAC_FLEN);
+ gswip_switch_w(priv, VLAN_ETH_FRAME_LEN + 8 + ETH_FCS_LEN,
+ GSWIP_MAC_FLEN);
gswip_switch_mask(priv, 0, GSWIP_BM_QUEUE_GCTRL_GL_MOD,
GSWIP_BM_QUEUE_GCTRL);