[RFC PATCH v2 net-next 02/14] net: dsa: mt7530: fix phylink for port 5 and fix port 5 modes

[arinc9.unal@gmail.com]

From: Arınç ÜNAL <arinc.unal@arinc9.com>

There're two code paths for setting up port 5:

mt7530_setup()
-> mt7530_setup_port5()

mt753x_phylink_mac_config()
-> mt753x_mac_config()
   -> mt7530_mac_config()
      -> mt7530_setup_port5()

The first code path is supposed to run when PHY muxing is being used. In
this case, port 5 is somewhat of a hidden port. It won't be defined on the
devicetree so phylink can't be used to manage the port.

The second code path used to call mt7530_setup_port5() directly under case
5 on mt7530_phylink_mac_config() before it was moved to mt7530_mac_config()
with 88bdef8be9f6 ("net: dsa: mt7530: Extend device data ready for adding a
new hardware"). mt7530_setup_port5() will never run through this code path
because the current code on mt7530_setup() bypasses phylink for all cases
of port 5.

Fix this by leaving it to phylink if port 5 is used as a CPU, DSA, or user
port. For the cases of PHY muxing or the port being disabled, call
mt7530_setup_port5() directly from mt7530_setup() without involving
phylink.

Move setting the interface and P5_DISABLED mode to a more specific
location. They're supposed to be overwritten if PHY muxing is detected.

Add comments which explain the process.

Tested-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
---
 drivers/net/dsa/mt7530.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 31ef70f0cd12..a00aabe4987e 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -2288,16 +2288,19 @@ mt7530_setup(struct dsa_switch *ds)
 		return ret;
 
 	/* Setup port 5 */
-	priv->p5_intf_sel = P5_DISABLED;
-	interface = PHY_INTERFACE_MODE_NA;
-
 	if (!dsa_is_unused_port(ds, 5)) {
+		/* Set the interface selection of port 5 to GMAC5 when it's used
+		 * as a CPU, DSA, or user port. Let phylink handle the rest.
+		 */
 		priv->p5_intf_sel = P5_INTF_SEL_GMAC5;
-		ret = of_get_phy_mode(dsa_to_port(ds, 5)->dn, &interface);
-		if (ret && ret != -ENODEV)
-			return ret;
 	} else {
-		/* Scan the ethernet nodes. look for GMAC1, lookup used phy */
+		/* Scan the ethernet nodes. Look for GMAC1, lookup the used PHY.
+		 * Set priv->p5_intf_sel to P5_DISABLED first, then overwrite it
+		 * if PHY muxing is detected.
+		 */
+		priv->p5_intf_sel = P5_DISABLED;
+		interface = PHY_INTERFACE_MODE_NA;
+
 		for_each_child_of_node(dn, mac_np) {
 			if (!of_device_is_compatible(mac_np,
 						     "mediatek,eth-mac"))
@@ -2328,6 +2331,8 @@ mt7530_setup(struct dsa_switch *ds)
 			of_node_put(phy_node);
 			break;
 		}
+
+		mt7530_setup_port5(ds, interface);
 	}
 
 #ifdef CONFIG_GPIOLIB
@@ -2338,8 +2343,6 @@ mt7530_setup(struct dsa_switch *ds)
 	}
 #endif /* CONFIG_GPIOLIB */
 
-	mt7530_setup_port5(ds, interface);
-
 	/* Flush the FDB table */
 	ret = mt7530_fdb_cmd(priv, MT7530_FDB_FLUSH, NULL);
 	if (ret < 0)
-- 
2.37.2