[PATCH] net: dsa: slave: Fix autoneg for phys on switch MDIO bus

When the ports phys are connected to the switches internal MDIO bus,
we need to connect the phy to the slave netdev, otherwise
auto-negotiation etc, does not work.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---

Hi Florian

Is this the right fix?

What i found is that ports on mv88E6171 we coming up as 10/half.  If i
forced a renegotiation with ethtool -r lan0, the phy would then goto
1000/full.

The code for phys on internal switch MDIO buses never connect the phy
to the device, only phys listed in DT get connected via
of_phy_connect(). By connecting the phy, the state machine is active
and does an autoneg when the slave interface is opened.

net/dsa/slave.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 6d1817449c36..ab03e00ffe8f 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c

@@ -489,11 +489,14 @@ static void dsa_slave_phy_setup(struct dsa_slave_priv *p,
 	/* We could not connect to a designated PHY, so use the switch internal
 	 * MDIO bus instead
 	 */
-	if (!p->phy)
+	if (!p->phy) {
 		p->phy = ds->slave_mii_bus->phy_map[p->port];
-	else
+		phy_connect_direct(slave_dev, p->phy, dsa_slave_adjust_link,
+				   p->phy_interface);
+	} else {
 		pr_info("attached PHY at address %d [%s]\n",
 			p->phy->addr, p->phy->drv->name);
+	}
 }
 
 int dsa_slave_suspend(struct net_device *slave_dev)

-- 
2.1.3

On 11/05/2014 10:47 AM, Andrew Lunn wrote:

When the ports phys are connected to the switches internal MDIO bus,
we need to connect the phy to the slave netdev, otherwise
auto-negotiation etc, does not work.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---

Hi Florian

Is this the right fix?

What i found is that ports on mv88E6171 we coming up as 10/half.  If i
forced a renegotiation with ethtool -r lan0, the phy would then goto
1000/full.

The code for phys on internal switch MDIO buses never connect the phy
to the device, only phys listed in DT get connected via
of_phy_connect(). By connecting the phy, the state machine is active
and does an autoneg when the slave interface is opened.

This looks fine to me, I think we might want to revisit/nuke the code at
the end of dsa_slave_create since it:

- is racy: netif_carrier_off() is called before register_netdev()
- is double racy: we should be bound to a PHY before calling
register_netdev() otherwise there could be MDIO accesses done to that
PHY without an actual PHY being registered

From: Andrew Lunn <andrew@lunn.ch>
Date: Wed,  5 Nov 2014 19:47:28 +0100

When the ports phys are connected to the switches internal MDIO bus,
we need to connect the phy to the slave netdev, otherwise
auto-negotiation etc, does not work.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>

Applied, thanks Andrew.