net: dsa: mt7530: do not set MT7530_P5_DIS when PHY muxing is being used

DSA initalises the ds->num_ports amount of ports in
dsa_switch_touch_ports(). When the PHY muxing feature is in use, port 5
won't be defined in the device tree. Because of this, the type member of
the dsa_port structure for this port will be assigned DSA_PORT_TYPE_UNUSED.
The dsa_port_setup() function calls ds->ops->port_disable() when the port
type is DSA_PORT_TYPE_UNUSED.

The MT7530_P5_DIS bit is unset in mt7530_setup() when PHY muxing is being
used. mt7530_port_disable() which is assigned to ds->ops->port_disable() is
called afterwards. Currently, mt7530_port_disable() sets MT7530_P5_DIS
which breaks network connectivity when PHY muxing is being used.

Therefore, do not set MT7530_P5_DIS when PHY muxing is being used.

Fixes: 377174c5 ("net: dsa: mt7530: move MT753X_MTRAP operations for MT7530")
Reported-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20240428-for-netnext-mt7530-do-not-disable-port5-when-phy-muxing-v2-1-bb7c37d293f8@arinc9.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/dsa/mt7530.c

@@ -1220,7 +1220,8 @@ mt7530_port_disable(struct dsa_switch *ds, int port)
 	if (priv->id != ID_MT7530 && priv->id != ID_MT7621)
 		return;
 
-	if (port == 5)
+	/* Do not set MT7530_P5_DIS when port 5 is being used for PHY muxing. */
+	if (port == 5 && priv->p5_mode == GMAC5)
 		mt7530_set(priv, MT753X_MTRAP, MT7530_P5_DIS);
 	else if (port == 6)
 		mt7530_set(priv, MT753X_MTRAP, MT7530_P6_DIS);