This is a note to let you know that I've just added the patch titled
net: dsa: vsc73xx: fix MTU configuration
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-vsc73xx-fix-mtu-configuration.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 6120626742fb36397bd1202e7aa182b1f4f89166
Author: Pawel Dembicki <paweldembicki@xxxxxxxxx>
Date: Wed Jun 28 21:43:27 2023 +0200
net: dsa: vsc73xx: fix MTU configuration
[ Upstream commit 3cf62c8177adb0db9e15c8b898c44f997acf3ebf ]
Switch in MAXLEN register stores the maximum size of a data frame.
The MTU size is 18 bytes smaller than the frame size.
The current settings are causing problems with packet forwarding.
This patch fixes the MTU settings to proper values.
Fixes: fb77ffc6ec86 ("net: dsa: vsc73xx: make the MTU configurable")
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Pawel Dembicki <paweldembicki@xxxxxxxxx>
Reviewed-by: Vladimir Oltean <olteanv@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230628194327.1765644-1-paweldembicki@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/dsa/vitesse-vsc73xx-core.c b/drivers/net/dsa/vitesse-vsc73xx-core.c
index a4b1447ff0557..0c0bc78b1788e 100644
--- a/drivers/net/dsa/vitesse-vsc73xx-core.c
+++ b/drivers/net/dsa/vitesse-vsc73xx-core.c
@@ -1025,17 +1025,17 @@ static int vsc73xx_change_mtu(struct dsa_switch *ds, int port, int new_mtu)
struct vsc73xx *vsc = ds->priv;
return vsc73xx_write(vsc, VSC73XX_BLOCK_MAC, port,
- VSC73XX_MAXLEN, new_mtu);
+ VSC73XX_MAXLEN, new_mtu + ETH_HLEN + ETH_FCS_LEN);
}
/* According to application not "VSC7398 Jumbo Frames" setting
- * up the MTU to 9.6 KB does not affect the performance on standard
+ * up the frame size to 9.6 KB does not affect the performance on standard
* frames. It is clear from the application note that
* "9.6 kilobytes" == 9600 bytes.
*/
static int vsc73xx_get_max_mtu(struct dsa_switch *ds, int port)
{
- return 9600;
+ return 9600 - ETH_HLEN - ETH_FCS_LEN;
}
static const struct dsa_switch_ops vsc73xx_ds_ops = {
