This is a note to let you know that I've just added the patch titled
net: dsa: qca8k: reset cpu port on MTU change
to the 5.18-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-qca8k-reset-cpu-port-on-mtu-change.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 386228c694bf1e7a7688e44412cb33500b0ac585 Mon Sep 17 00:00:00 2001
From: Christian Marangi <ansuelsmth@xxxxxxxxx>
Date: Tue, 21 Jun 2022 17:11:22 +0200
Subject: net: dsa: qca8k: reset cpu port on MTU change
From: Christian Marangi <ansuelsmth@xxxxxxxxx>
commit 386228c694bf1e7a7688e44412cb33500b0ac585 upstream.
It was discovered that the Documentation lacks of a fundamental detail
on how to correctly change the MAX_FRAME_SIZE of the switch.
In fact if the MAX_FRAME_SIZE is changed while the cpu port is on, the
switch panics and cease to send any packet. This cause the mgmt ethernet
system to not receive any packet (the slow fallback still works) and
makes the device not reachable. To recover from this a switch reset is
required.
To correctly handle this, turn off the cpu ports before changing the
MAX_FRAME_SIZE and turn on again after the value is applied.
Fixes: f58d2598cf70 ("net: dsa: qca8k: implement the port MTU callbacks")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>
Link: https://lore.kernel.org/r/20220621151122.10220-1-ansuelsmth@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/dsa/qca8k.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -2372,7 +2372,7 @@ static int
qca8k_port_change_mtu(struct dsa_switch *ds, int port, int new_mtu)
{
struct qca8k_priv *priv = ds->priv;
- int i, mtu = 0;
+ int ret, i, mtu = 0;
priv->port_mtu[port] = new_mtu;
@@ -2380,8 +2380,27 @@ qca8k_port_change_mtu(struct dsa_switch
if (priv->port_mtu[i] > mtu)
mtu = priv->port_mtu[i];
+ /* To change the MAX_FRAME_SIZE the cpu ports must be off or
+ * the switch panics.
+ * Turn off both cpu ports before applying the new value to prevent
+ * this.
+ */
+ if (priv->port_sts[0].enabled)
+ qca8k_port_set_status(priv, 0, 0);
+
+ if (priv->port_sts[6].enabled)
+ qca8k_port_set_status(priv, 6, 0);
+
/* Include L2 header / FCS length */
- return qca8k_write(priv, QCA8K_MAX_FRAME_SIZE, mtu + ETH_HLEN + ETH_FCS_LEN);
+ ret = qca8k_write(priv, QCA8K_MAX_FRAME_SIZE, mtu + ETH_HLEN + ETH_FCS_LEN);
+
+ if (priv->port_sts[0].enabled)
+ qca8k_port_set_status(priv, 0, 1);
+
+ if (priv->port_sts[6].enabled)
+ qca8k_port_set_status(priv, 6, 1);
+
+ return ret;
}
static int
Patches currently in stable-queue which might be from ansuelsmth@xxxxxxxxx are
queue-5.18/net-dsa-qca8k-reset-cpu-port-on-mtu-change.patch
