netdev - [PATCH] net: fec: manage corner deferred probe condition

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Date:   Sun, 15 Jan 2023 18:49:10 +0100
From:   Pierluigi Passaro <pierluigi.passaro@...il.com>
To:     wei.fang@....com, shenwei.wang@....com, xiaoning.wang@....com,
        linux-imx@....com, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     eran.m@...iscite.com, nate.d@...iscite.com,
        francesco.f@...iscite.com, pierluigi.p@...iscite.com
Subject: [PATCH] net: fec: manage corner deferred probe condition

For dual fec interfaces, external phys can only be configured by fec0.
When the function of_mdiobus_register return -EPROBE_DEFER, the driver
is lately called to manage fec1, which wrongly register its mii_bus as
fec0_mii_bus.
When fec0 retry the probe, the previous assignement prevent the MDIO bus
registration.
Use a static boolean to trace the orginal MDIO bus deferred probe and
prevent further registrations until the fec0 registration completed
succesfully.

Signed-off-by: Pierluigi Passaro <pierluigi.p@...iscite.com>
---
 drivers/net/ethernet/freescale/fec_main.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 644f3c963730..b4ca3bd4283f 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -2284,6 +2284,18 @@ static int fec_enet_mii_init(struct platform_device *pdev)
 	int err = -ENXIO;
 	u32 mii_speed, holdtime;
 	u32 bus_freq;
+	static bool wait_for_mdio_bus = false;
+
+	bus_freq = 2500000; /* 2.5MHz by default */
+	node = of_get_child_by_name(pdev->dev.of_node, "mdio");
+	if (node) {
+		wait_for_mdio_bus = false;
+		of_property_read_u32(node, "clock-frequency", &bus_freq);
+		suppress_preamble = of_property_read_bool(node,
+							  "suppress-preamble");
+	}
+	if (wait_for_mdio_bus)
+		return -EPROBE_DEFER;
 
 	/*
 	 * The i.MX28 dual fec interfaces are not equal.
@@ -2311,14 +2323,6 @@ static int fec_enet_mii_init(struct platform_device *pdev)
 		return -ENOENT;
 	}
 
-	bus_freq = 2500000; /* 2.5MHz by default */
-	node = of_get_child_by_name(pdev->dev.of_node, "mdio");
-	if (node) {
-		of_property_read_u32(node, "clock-frequency", &bus_freq);
-		suppress_preamble = of_property_read_bool(node,
-							  "suppress-preamble");
-	}
-
 	/*
 	 * Set MII speed (= clk_get_rate() / 2 * phy_speed)
 	 *
@@ -2389,6 +2393,8 @@ static int fec_enet_mii_init(struct platform_device *pdev)
 	fep->mii_bus->parent = &pdev->dev;
 
 	err = of_mdiobus_register(fep->mii_bus, node);
+	if (err == -EPROBE_DEFER)
+		wait_for_mdio_bus = true;
 	if (err)
 		goto err_out_free_mdiobus;
 	of_node_put(node);
-- 
2.37.2