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From:   Pierluigi Passaro <pierluigi.passaro@gmail.com>
To:     wei.fang@nxp.com, shenwei.wang@nxp.com, xiaoning.wang@nxp.com,
        linux-imx@nxp.com, davem@davemloft.net, edumazet@google.com,
        kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     eran.m@variscite.com, nate.d@variscite.com,
        francesco.f@variscite.com, pierluigi.p@variscite.com
Subject: [PATCH] net: fec: manage corner deferred probe condition
Date:   Sun, 15 Jan 2023 18:49:10 +0100
Message-Id: <20230115174910.18353-1-pierluigi.p@variscite.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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@variscite.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