net: dsa: Make mdio bus optional

The switch may want to instantiate its own MDIO bus. Only do it
centrally if the switch has not already created one, and the read op
is implemented.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 11 deletions

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 221ebde4318d..6c314f300424 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -340,17 +340,18 @@ static int dsa_switch_setup_one(struct dsa_switch *ds, struct device *parent)
         if (ret < 0)
                 goto out;
 
-        ds->slave_mii_bus = devm_mdiobus_alloc(parent);
-        if (ds->slave_mii_bus == NULL) {
-                ret = -ENOMEM;
-                goto out;
-        }
-        dsa_slave_mii_bus_init(ds);
-
-        ret = mdiobus_register(ds->slave_mii_bus);
-        if (ret < 0)
-                goto out;
+        if (!ds->slave_mii_bus && drv->phy_read) {
+                ds->slave_mii_bus = devm_mdiobus_alloc(parent);
+                if (!ds->slave_mii_bus) {
+                        ret = -ENOMEM;
+                        goto out;
+                }
+                dsa_slave_mii_bus_init(ds);
 
+                ret = mdiobus_register(ds->slave_mii_bus);
+                if (ret < 0)
+                        goto out;
+        }
 
         /*
          * Create network devices for physical switch ports.
@@ -493,7 +494,8 @@ static void dsa_switch_destroy(struct dsa_switch *ds)
                 dsa_cpu_dsa_destroy(ds->ports[port].dn);
         }
 
-        mdiobus_unregister(ds->slave_mii_bus);
+        if (ds->slave_mii_bus && ds->drv->phy_read)
+                mdiobus_unregister(ds->slave_mii_bus);
 }
 
 #ifdef CONFIG_PM_SLEEP