netdev - [PATCH net-next] net: stmmac: don't create the MDIO bus if there's no mdio node on DT

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Date: Tue,  8 Aug 2023 14:02:54 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jose Abreu <joabreu@...opsys.com>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alex Elder <elder@...aro.org>,
	Srini Kandagatla <srinivas.kandagatla@...aro.org>,
	Andrew Halaney <ahalaney@...hat.com>
Cc: netdev@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH net-next] net: stmmac: don't create the MDIO bus if there's no mdio node on DT

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

The stmmac_dt_phy() function that parses the device-tree node of the MAC
and allocates the MDIO and PHY resources misses one use-case: when the
MAC doesn't have a fixed link but also doesn't define its own mdio bus
on the device tree and instead shares the MDIO lines with a different
MAC with its PHY phandle reaching over into a different node.

As this function could also use some more readability, rework it to
handle this use-case and simplify the code.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 .../ethernet/stmicro/stmmac/stmmac_platform.c | 26 +++++++++----------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index be8e79c7aa34..91844673df43 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -320,12 +320,14 @@ static int stmmac_mtl_setup(struct platform_device *pdev,
 static int stmmac_dt_phy(struct plat_stmmacenet_data *plat,
 			 struct device_node *np, struct device *dev)
 {
-	bool mdio = !of_phy_is_fixed_link(np);
 	static const struct of_device_id need_mdio_ids[] = {
 		{ .compatible = "snps,dwc-qos-ethernet-4.10" },
 		{},
 	};
 
+	if (of_phy_is_fixed_link(np))
+		return 0;
+
 	if (of_match_node(need_mdio_ids, np)) {
 		plat->mdio_node = of_get_child_by_name(np, "mdio");
 	} else {
@@ -340,20 +342,18 @@ static int stmmac_dt_phy(struct plat_stmmacenet_data *plat,
 		}
 	}
 
-	if (plat->mdio_node) {
-		dev_dbg(dev, "Found MDIO subnode\n");
-		mdio = true;
-	}
+	if (!plat->mdio_node)
+		return 0;
 
-	if (mdio) {
-		plat->mdio_bus_data =
-			devm_kzalloc(dev, sizeof(struct stmmac_mdio_bus_data),
-				     GFP_KERNEL);
-		if (!plat->mdio_bus_data)
-			return -ENOMEM;
+	dev_dbg(dev, "Found MDIO subnode\n");
 
-		plat->mdio_bus_data->needs_reset = true;
-	}
+	plat->mdio_bus_data = devm_kzalloc(dev,
+					   sizeof(struct stmmac_mdio_bus_data),
+					   GFP_KERNEL);
+	if (!plat->mdio_bus_data)
+		return -ENOMEM;
+
+	plat->mdio_bus_data->needs_reset = true;
 
 	return 0;
 }
-- 
2.39.2