Re: [PATCH v1 1/2] driver core: fw_devlink: Add support for FWNODE_FLAG_BROKEN_PARENT

Andrew Lunn
2021-08-26T20:53:17Z

> The DT node in [2] is probed by realtek_smi_probe() [3]. The call flow is:
> realtek_smi_probe()
> -> dsa_register_switch()
> -> dsa_switch_probe()
> -> dsa_tree_setup()
> -> dsa_tree_setup_switches()
> -> dsa_switch_setup()
> -> ds->ops->setup(ds)
> -> rtl8366rb_setup()
> -> realtek_smi_setup_mdio()
> -> of_mdiobus_register()
> This scans the MDIO bus/DT and device_add()s the PHYs
> -> dsa_port_setup()
> -> dsa_port_link_register_of()
> -> dsa_port_phylink_register()
> -> phylink_of_phy_connect()
> -> phylink_fwnode_phy_connect()
> -> phy_attach_direct()
> This checks if PHY device has already probed (by
> checking for dev->driver). If not, it forces the
> probe of the PHY using one of the generic PHY
> drivers.
>
> So within dsa_register_switch() the PHY device is added and then
> expected to have probed in the same thread/calling context. As stated
> earlier, this is not guaranteed by the driver core.

Have you looked at:

commit 16983507742cbcaa5592af530872a82e82fb9c51
Author: Heiner Kallweit <hkallweit1@gmail.com>
Date: Fri Mar 27 01:00:22 2020 +0100

net: phy: probe PHY drivers synchronously

See the full commit message, but the code change is:

iff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 3b8f6b0b47b5..d543df282365 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -2577,6 +2577,7 @@ 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) {

How does this add to the overall picture?

Andrew