netdev - [net-next,v3 2/2] ravb: Add support for an optional MDIO mode

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Date: Mon, 11 Mar 2024 15:11:06 +0100
From: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
To: Sergey Shtylyov <s.shtylyov@....ru>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	Biju Das <biju.das.jz@...renesas.com>,
	netdev@...r.kernel.org,
	devicetree@...r.kernel.org
Cc: linux-renesas-soc@...r.kernel.org,
	Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
Subject: [net-next,v3 2/2] ravb: Add support for an optional MDIO mode

The driver used the DT node of the device itself when registering the
MDIO bus. While this works, it creates a problem: it forces any MDIO bus
properties to also be set on the devices DT node. This mixes the
properties of two distinctly different things and is confusing.

This change adds support for an optional mdio node to be defined as a
child to the device DT node. The child node can then be used to describe
MDIO bus properties that the MDIO core can act on when registering the
bus.

If no mdio child node is found the driver fallback to the old behavior
and register the MDIO bus using the device DT node. This change is
backward compatible with old bindings in use.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
Reviewed-by: Sergey Shtylyov <s.shtylyov@....ru>
---
* Changes since v2
- Use DT node instead of OF ode in commit message.
- Update punctuation in commit message.
- Simplify the node selection in the driver.
---
 drivers/net/ethernet/renesas/ravb_main.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index fa48ff4aba2d..b6adf608ebfa 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -2564,6 +2564,7 @@ static int ravb_mdio_init(struct ravb_private *priv)
 {
 	struct platform_device *pdev = priv->pdev;
 	struct device *dev = &pdev->dev;
+	struct device_node *mdio_node;
 	struct phy_device *phydev;
 	struct device_node *pn;
 	int error;
@@ -2583,7 +2584,13 @@ static int ravb_mdio_init(struct ravb_private *priv)
 		 pdev->name, pdev->id);
 
 	/* Register MDIO bus */
-	error = of_mdiobus_register(priv->mii_bus, dev->of_node);
+	mdio_node = of_get_child_by_name(dev->of_node, "mdio");
+	if (!mdio_node) {
+		/* backwards compatibility for DT lacking mdio subnode */
+		mdio_node = of_node_get(dev->of_node);
+	}
+	error = of_mdiobus_register(priv->mii_bus, mdio_node);
+	of_node_put(mdio_node);
 	if (error)
 		goto out_free_bus;
 
-- 
2.44.0