net: phy: don't try to setup PHY-driven SFP cages when using genphy

[ Upstream commit 5a0082e ]

We don't have support for PHY-driver SFP cages with the genphy code.

On top of that, it was found by sashiko that running
sfp_bus_add_upstream() for genphy deadlocks, as for genphy the PHY
probing runs under RTNL, which isn't the case for non-genphy drivers.

This problem was reproduced, and does lead to a deadlock on RTNL.

Before the blamed commit, the phy_sfp_probe() call was made by
individual PHY drivers, so there was no way to get to the SFP probing
path when using genphy.

Let's therefore only run phy_sfp_probe when not using genphy.

Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
Fixes: bad869b ("net: phy: Only rely on phy_port for PHY-driven SFP")
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20260604092819.723505-5-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: minimaxwell

drivers/net/phy/phy_device.c

@@ -3528,9 +3528,15 @@ static int phy_setup_ports(struct phy_device *phydev)
 	if (ret)
 		return ret;
 
-	ret = phy_sfp_probe(phydev);
-	if (ret)
-		goto out;
+	/* We don't support SFP with genphy drivers. Also, genphy driver
+	 * binding occurs with RTNL help, which will deadlock the call to
+	 * sfp_bus_add_upstream().
+	 */
+	if (!phydev->is_genphy_driven) {
+		ret = phy_sfp_probe(phydev);
+		if (ret)
+			goto out;
+	}
 
 	if (phydev->n_ports < phydev->max_n_ports) {
 		ret = phy_default_setup_single_port(phydev);