netdev - [PATCH net-next v2] net: phy: probe PHY drivers synchronously

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Message-ID: <612b81d5-c4c1-5e20-a667-893eeeef0bf5@gmail.com>
Date:   Fri, 27 Mar 2020 01:00:22 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        David Miller <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net-next v2] net: phy: probe PHY drivers synchronously

If we have scenarios like

mdiobus_register()
	-> loads PHY driver module(s)
	-> registers PHY driver(s)
	-> may schedule async probe
phydev = mdiobus_get_phy()
<phydev action involving PHY driver>

or

phydev = phy_device_create()
	-> loads PHY driver module
	-> registers PHY driver
	-> may schedule async probe
<phydev action involving PHY driver>

then we expect the PHY driver to be bound to the phydev when triggering
the action. This may not be the case in case of asynchronous probing.
Therefore ensure that PHY drivers are probed synchronously.

Default still is sync probing, except async probing is explicitly
requested. I saw some comments that the intention is to promote
async probing for more parallelism in boot process and want to be
prepared for the case that the default is changed to async probing.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/phy/phy_device.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index d6024b678..ac2784192 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -2575,6 +2575,7 @@ int phy_driver_register(struct phy_driver *new_driver, struct module *owner)
 	new_driver->mdiodrv.driver.probe = phy_probe;
 	new_driver->mdiodrv.driver.remove = phy_remove;
 	new_driver->mdiodrv.driver.owner = owner;
+	new_driver->mdiodrv.driver.probe_type = PROBE_FORCE_SYNCHRONOUS;
 
 	retval = driver_register(&new_driver->mdiodrv.driver);
 	if (retval) {
-- 
2.26.0