[PATCH v2] net: dsa: fix mv88e6xxx switches

[PATCH v2] net: dsa: fix mv88e6xxx switches

[Russell King]

Since commit 76e398a62712 ("net: dsa: use switchdev obj for VLAN add/del
ops"), the Marvell 88E6xxx switch has been unable to pass traffic
between ports - any received traffic is discarded by the switch.
Taking a port out of bridge mode and configuring a vlan on it also the
port to start passing traffic.

With the debugfs files re-instated to allow debug of this issue by
comparing the register settings between the working and non-working
case, the reason becomes clear:

     GLOBAL GLOBAL2 SERDES   0    1    2    3    4    5    6
- 7:  1111    707f    2001     2    2    2    2    2    0    2
+ 7:  1111    707f    2001     1    1    1    1    1    0    1

Register 7 for the ports is the default vlan tag register, and in the
non-working setup, it has been set to 2, despite vlan 2 not being
configured.  This causes the switch to drop all packets coming in to
these ports.  The working setup has the default vlan tag register set
to 1, which is the default vlan when none is configured.

Inspection of the code reveals why.  The code prior to this commit
was:

-		for (vid = vlan->vid_begin; vid <= vlan->vid_end; ++vid) {
...
-			if (!err && vlan->flags & BRIDGE_VLAN_INFO_PVID)
-				err = ds->drv->port_pvid_set(ds, p->port, vid);

but the new code is:

+	for (vid = vlan->vid_begin; vid <= vlan->vid_end; ++vid) {
...
+	}
...
+	if (pvid)
+		err = _mv88e6xxx_port_pvid_set(ds, port, vid);

This causes the new code to always set the default vlan to one higher
than the old code.

Fix this.

Fixes: 76e398a62712 ("net: dsa: use switchdev obj for VLAN add/del ops")
Cc: <stable@vger.kernel.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
v2: simpler fix

 drivers/net/dsa/mv88e6xxx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/dsa/mv88e6xxx.c b/drivers/net/dsa/mv88e6xxx.c
index b06dba05594a..84b0a93559b2 100644
--- a/drivers/net/dsa/mv88e6xxx.c
+++ b/drivers/net/dsa/mv88e6xxx.c
@@ -1519,7 +1519,7 @@ int mv88e6xxx_port_vlan_add(struct dsa_switch *ds, int port,
 
 	/* no PVID with ranges, otherwise it's a bug */
 	if (pvid)
-		err = _mv88e6xxx_port_pvid_set(ds, port, vid);
+		err = _mv88e6xxx_port_pvid_set(ds, port, vlan->vid_end);
 unlock:
 	mutex_unlock(&ps->smi_mutex);
 
-- 
2.1.0

Re: [PATCH v2] net: dsa: fix mv88e6xxx switches

[David Miller]

From: Russell King <rmk+kernel@arm.linux.org.uk>
Date: Sun, 24 Jan 2016 09:22:05 +0000

> Since commit 76e398a62712 ("net: dsa: use switchdev obj for VLAN add/del
> ops"), the Marvell 88E6xxx switch has been unable to pass traffic
> between ports - any received traffic is discarded by the switch.
> Taking a port out of bridge mode and configuring a vlan on it also the
> port to start passing traffic.
> 
> With the debugfs files re-instated to allow debug of this issue by
> comparing the register settings between the working and non-working
> case, the reason becomes clear:
> 
>      GLOBAL GLOBAL2 SERDES   0    1    2    3    4    5    6
> - 7:  1111    707f    2001     2    2    2    2    2    0    2
> + 7:  1111    707f    2001     1    1    1    1    1    0    1
> 
> Register 7 for the ports is the default vlan tag register, and in the
> non-working setup, it has been set to 2, despite vlan 2 not being
> configured.  This causes the switch to drop all packets coming in to
> these ports.  The working setup has the default vlan tag register set
> to 1, which is the default vlan when none is configured.
> 
> Inspection of the code reveals why.  The code prior to this commit
> was:
> 
> -		for (vid = vlan->vid_begin; vid <= vlan->vid_end; ++vid) {
> ...
> -			if (!err && vlan->flags & BRIDGE_VLAN_INFO_PVID)
> -				err = ds->drv->port_pvid_set(ds, p->port, vid);
> 
> but the new code is:
> 
> +	for (vid = vlan->vid_begin; vid <= vlan->vid_end; ++vid) {
> ...
> +	}
> ...
> +	if (pvid)
> +		err = _mv88e6xxx_port_pvid_set(ds, port, vid);
> 
> This causes the new code to always set the default vlan to one higher
> than the old code.
> 
> Fix this.
> 
> Fixes: 76e398a62712 ("net: dsa: use switchdev obj for VLAN add/del ops")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Applied and queued up for -stable, thanks Russell.