linux-kernel - [PATCH AUTOSEL 4.19 02/66] net: phy: probe PHY drivers synchronously

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Date:   Sat, 11 Apr 2020 19:10:59 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 02/66] net: phy: probe PHY drivers synchronously

From: Heiner Kallweit <hkallweit1@...il.com>

[ Upstream commit 16983507742cbcaa5592af530872a82e82fb9c51 ]

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>
Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 302d183beb9e8..9ae121cb6dc11 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1939,6 +1939,7 @@ 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;
 
 	/* 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
-- 
2.20.1