netdev - [PATCH net] net: phy: replace preliminary fix for PHY driver sometimes not binding to the device

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Message-ID: <1bafaa75-18a2-87a2-a9cb-01b951c1d1f7@gmail.com>
Date:   Mon, 24 Dec 2018 12:21:12 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        David Miller <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Norbert Jurkeit <norbert.jurkeit@....de>,
        Frank Crawford <frank@...wford.emu.id.au>
Subject: [PATCH net] net: phy: replace preliminary fix for PHY driver
 sometimes not binding to the device

phy_device_create() uses request_module() to load the PHY driver module
based on the PHY ID of the device. There is some timing issue which
sometimes prevents the PHY driver to bind to the device. In such cases
the genphy driver is used what can cause problems if genphy isn't
compatible with the respective PHY.
It turned out that the first fix can fix the issue in some but not all
cases. Moving the call to device_initialize() before the call to
request_module() was reported to fix the issue.
I can't explain where the root cause of the issue is and why this fix
works. AFAICS device_initialize() just initializes the device struct
w/o doing anything that could interfere with e.g. bus_add_driver().
This patch removes the first preliminary fix attempt.

Reference:
https://bugzilla.redhat.com/show_bug.cgi?id=1650984

Fixes: c85ddecae6e5 ("net: phy: add workaround for issue where PHY driver doesn't bind to the device")
Tested-by: Norbert Jurkeit <norbert.jurkeit@....de>
Tested-by: Frank Crawford <frank@...wford.emu.id.au>
Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/phy/phy_device.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 26c41ede5..ac0a83c7d 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -579,6 +579,7 @@ struct phy_device *phy_device_create(struct mii_bus *bus, int addr, int phy_id,
 		dev->c45_ids = *c45_ids;
 	dev->irq = bus->irq[addr];
 	dev_set_name(&mdiodev->dev, PHY_ID_FMT, bus->id, addr);
+	device_initialize(&mdiodev->dev);
 
 	dev->state = PHY_DOWN;
 
@@ -598,8 +599,6 @@ struct phy_device *phy_device_create(struct mii_bus *bus, int addr, int phy_id,
 	 */
 	request_module(MDIO_MODULE_PREFIX MDIO_ID_FMT, MDIO_ID_ARGS(phy_id));
 
-	device_initialize(&mdiodev->dev);
-
 	return dev;
 }
 EXPORT_SYMBOL(phy_device_create);
@@ -2191,14 +2190,6 @@ int phy_driver_register(struct phy_driver *new_driver, struct module *owner)
 	new_driver->mdiodrv.driver.remove = phy_remove;
 	new_driver->mdiodrv.driver.owner = owner;
 
-	/* The following works around an issue where the PHY driver doesn't bind
-	 * to the device, resulting in the genphy driver being used instead of
-	 * the dedicated driver. The root cause of the issue isn't known yet
-	 * and seems to be in the base driver core. Once this is fixed we may
-	 * remove this workaround.
-	 */
-	new_driver->mdiodrv.driver.probe_type = PROBE_FORCE_SYNCHRONOUS;
-
 	retval = driver_register(&new_driver->mdiodrv.driver);
 	if (retval) {
 		pr_err("%s: Error %d in registering driver\n",
-- 
2.20.1