This is a note to let you know that I've just added the patch titled
net: dsa: b53: fix max MTU for 1g switches
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-dsa-b53-fix-max-mtu-for-1g-switches.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d1041fd2215060f338f3a371890b3626eaa18b14
Author: Jonas Gorski <jonas.gorski@xxxxxxxxx>
Date: Fri Oct 4 10:47:18 2024 +0200
net: dsa: b53: fix max MTU for 1g switches
[ Upstream commit 680a8217dc00dc7e7da57888b3c053289b60eb2b ]
JMS_MAX_SIZE is the ethernet frame length, not the MTU, which is payload
without ethernet headers.
According to the datasheets maximum supported frame length for most
gigabyte swithes is 9720 bytes, so convert that to the expected MTU when
using VLAN tagged frames.
Fixes: 6ae5834b983a ("net: dsa: b53: add MTU configuration support")
Signed-off-by: Jonas Gorski <jonas.gorski@xxxxxxxxx>
Reviewed-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
index 03047486b9b85..be1550332326a 100644
--- a/drivers/net/dsa/b53/b53_common.c
+++ b/drivers/net/dsa/b53/b53_common.c
@@ -27,6 +27,7 @@
#include <linux/phylink.h>
#include <linux/etherdevice.h>
#include <linux/if_bridge.h>
+#include <linux/if_vlan.h>
#include <net/dsa.h>
#include "b53_regs.h"
@@ -224,6 +225,8 @@ static const struct b53_mib_desc b53_mibs_58xx[] = {
#define B53_MIBS_58XX_SIZE ARRAY_SIZE(b53_mibs_58xx)
+#define B53_MAX_MTU (9720 - ETH_HLEN - VLAN_HLEN - ETH_FCS_LEN)
+
static int b53_do_vlan_op(struct b53_device *dev, u8 op)
{
unsigned int i;
@@ -2234,7 +2237,7 @@ static int b53_change_mtu(struct dsa_switch *ds, int port, int mtu)
static int b53_get_max_mtu(struct dsa_switch *ds, int port)
{
- return JMS_MAX_SIZE;
+ return B53_MAX_MTU;
}
static const struct dsa_switch_ops b53_switch_ops = {
