Similar to the situation described for sja1105 in commit 1f9fc48fd302
("net: dsa: sja1105: fix reception from VLAN-unaware bridges"), the
vsc73xx driver uses tag_8021q and doesn't need the ds->untag_bridge_pvid
request. In fact, this option breaks packet reception.

The ds->untag_bridge_pvid option strips VLANs from packets received on
VLAN-unaware bridge ports. But those VLANs should already be stripped
by tag_vsc73xx_8021q.c as part of vsc73xx_rcv() - they are not VLANs in
VLAN-unaware mode, but DSA tags. Thus, dsa_software_vlan_untag() tries
to untag a VLAN that doesn't exist, corrupting the packet.

Fixes: 93e4649efa96 ("net: dsa: provide a software untagging function on RX for VLAN-aware bridges")
Tested-by: Pawel Dembicki <paweldembicki@gmail.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
v1->v2:
- retarget to 'net'
- rewrite commit message

Link to v1:
https://lore.kernel.org/netdev/20241008104657.3549151-1-vladimir.oltean@nxp.com/

 drivers/net/dsa/vitesse-vsc73xx-core.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/net/dsa/vitesse-vsc73xx-core.c b/drivers/net/dsa/vitesse-vsc73xx-core.c
index e4b98fd51643..f18aa321053d 100644
--- a/drivers/net/dsa/vitesse-vsc73xx-core.c
+++ b/drivers/net/dsa/vitesse-vsc73xx-core.c
@@ -851,7 +851,6 @@ static int vsc73xx_setup(struct dsa_switch *ds)
 
 	dev_info(vsc->dev, "set up the switch\n");
 
-	ds->untag_bridge_pvid = true;
 	ds->max_num_bridges = DSA_TAG_8021Q_MAX_NUM_BRIDGES;
 	ds->fdb_isolation = true;
 
-- 
2.43.0

On Mon, Oct 14, 2024 at 5:30 PM Vladimir Oltean <vladimir.oltean@nxp.com> wrote:

> Similar to the situation described for sja1105 in commit 1f9fc48fd302
> ("net: dsa: sja1105: fix reception from VLAN-unaware bridges"), the
> vsc73xx driver uses tag_8021q and doesn't need the ds->untag_bridge_pvid
> request. In fact, this option breaks packet reception.
>
> The ds->untag_bridge_pvid option strips VLANs from packets received on
> VLAN-unaware bridge ports. But those VLANs should already be stripped
> by tag_vsc73xx_8021q.c as part of vsc73xx_rcv() - they are not VLANs in
> VLAN-unaware mode, but DSA tags. Thus, dsa_software_vlan_untag() tries
> to untag a VLAN that doesn't exist, corrupting the packet.
>
> Fixes: 93e4649efa96 ("net: dsa: provide a software untagging function on RX for VLAN-aware bridges")
> Tested-by: Pawel Dembicki <paweldembicki@gmail.com>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

On 10/14/24 08:30, Vladimir Oltean wrote:
> Similar to the situation described for sja1105 in commit 1f9fc48fd302
> ("net: dsa: sja1105: fix reception from VLAN-unaware bridges"), the
> vsc73xx driver uses tag_8021q and doesn't need the ds->untag_bridge_pvid
> request. In fact, this option breaks packet reception.
> 
> The ds->untag_bridge_pvid option strips VLANs from packets received on
> VLAN-unaware bridge ports. But those VLANs should already be stripped
> by tag_vsc73xx_8021q.c as part of vsc73xx_rcv() - they are not VLANs in
> VLAN-unaware mode, but DSA tags. Thus, dsa_software_vlan_untag() tries
> to untag a VLAN that doesn't exist, corrupting the packet.
> 
> Fixes: 93e4649efa96 ("net: dsa: provide a software untagging function on RX for VLAN-aware bridges")
> Tested-by: Pawel Dembicki <paweldembicki@gmail.com>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian