[PATCH v3] lan743x: correctly handle chips with internal PHY

[Sven Van Asbroeck <thesven73@gmail.com>]

From: Sven Van Asbroeck <thesven73@gmail.com>

Commit 6f197fb63850 ("lan743x: Added fixed link and RGMII support")
assumes that chips with an internal PHY will never have a devicetree
entry. This is incorrect: even for these chips, a devicetree entry
can be useful e.g. to pass the mac address from bootloader to chip:

    &pcie {
            status = "okay";

            host@0 {
                    reg = <0 0 0 0 0>;

                    #address-cells = <3>;
                    #size-cells = <2>;

                    lan7430: ethernet@0 {
                            /* LAN7430 with internal PHY */
                            compatible = "microchip,lan743x";
                            status = "okay";
                            reg = <0 0 0 0 0>;
                            /* filled in by bootloader */
                            local-mac-address = [00 00 00 00 00 00];
                    };
            };
    };

If a devicetree entry is present, the driver will not attach the chip
to its internal phy, and the chip will be non-operational.

Fix by tweaking the phy connection algorithm:
- first try to connect to a phy specified in the devicetree
  (could be 'real' phy, or just a 'fixed-link')
- if that doesn't succeed, try to connect to an internal phy, even
  if the chip has a devnode

Tested on a LAN7430 with internal PHY. I cannot test a device using
fixed-link, as I do not have access to one.

Fixes: 6f197fb63850 ("lan743x: Added fixed link and RGMII support")
Tested-by: Sven Van Asbroeck <thesven73@gmail.com> # lan7430
Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com>
---

v2 -> v3:
    Andrew Lunn: make patch truly minimal.

v1 -> v2:
    Andrew Lunn: keep patch minimal and correct, so keep open-coded version
    of of_phy_get_and_connect().

    Jakub Kicinski: fix e-mail address case.

Tree: v5.10-rc2

To: Andrew Lunn <andrew@lunn.ch>
To: Bryan Whitehead <bryan.whitehead@microchip.com>
To: "David S. Miller" <davem@davemloft.net>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>
Cc: Roelof Berg <rberg@berg-solutions.de>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

 drivers/net/ethernet/microchip/lan743x_main.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index f2d13e8d20f0..54d721ef3084 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -1021,9 +1021,9 @@ static int lan743x_phy_open(struct lan743x_adapter *adapter)
 
 	netdev = adapter->netdev;
 	phynode = of_node_get(adapter->pdev->dev.of_node);
-	adapter->phy_mode = PHY_INTERFACE_MODE_GMII;
 
 	if (phynode) {
+		/* try devicetree phy, or fixed link */
 		of_get_phy_mode(phynode, &adapter->phy_mode);
 
 		if (of_phy_is_fixed_link(phynode)) {
@@ -1039,13 +1039,15 @@ static int lan743x_phy_open(struct lan743x_adapter *adapter)
 					lan743x_phy_link_status_change, 0,
 					adapter->phy_mode);
 		of_node_put(phynode);
-		if (!phydev)
-			goto return_error;
-	} else {
+	}
+
+	if (!phydev) {
+		/* try internal phy */
 		phydev = phy_find_first(adapter->mdiobus);
 		if (!phydev)
 			goto return_error;
 
+		adapter->phy_mode = PHY_INTERFACE_MODE_GMII;
 		ret = phy_connect_direct(netdev, phydev,
 					 lan743x_phy_link_status_change,
 					 adapter->phy_mode);
-- 
2.17.1