[PATCH net-next v2 2/2] net: stmmac: Skip PHY attach if custom PCS is in use

[Zxyan Zhu <zxyan0222@gmail.com>]

When a platform provides a custom PCS via the pcs_init callback,
the MAC's phylink_pcs is already configured. In this case, phylink
validates against the PCS's supported interfaces and manages link
state through the PCS, so no traditional PHY device is needed.

Without this, stmmac_init_phy() falls through to the no-phy-node
path and errors out with "no phy found" when the DT has no
phy-handle for such interfaces.

Skip the PHY attach when priv->hw->phylink_pcs is already set and no
phy-handle is specified in the device tree.

Fixes: f0ef433fc264 ("net: stmmac: introduce pcs_init/pcs_exit stmmac operations")
Signed-off-by: Zxyan Zhu <zxyan0222@gmail.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 562d20830b94..044ed3b89247 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1346,6 +1346,10 @@ static int stmmac_init_phy(struct net_device *dev)
 		int addr = priv->plat->phy_addr;
 		struct phy_device *phydev;
 
+		/* If a custom PCS is in use, no PHY is needed */
+		if (priv->hw->phylink_pcs)
+			return 0;
+
 		if (addr < 0) {
 			netdev_err(priv->dev, "no phy found\n");
 			return -ENODEV;
-- 
2.34.1