Re: [PATCH v3 2/3] driver core: fw_devlink: Add support for FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD

[Andrew Lunn]

> There are cases where the children try to probe too quickly (before
> the parent has had time to set up all the resources it's setting up)
> and the child defers the probe. Even Andrew had an example of that
> with some ethernet driver where the deferred probe is attempted
> multiple times wasting time and then it eventually succeeds.

And i prefer an occasional EPROBE_DEFER over a broken Ethernet switch,
which is the current state. I'm happy to see optimisations, but not at
the expense of breaking working stuff.

> Also, this assumption that the child will be bound successfully upon
> addition forces the parent/child drivers to play initcall chicken

We have never had any initcall chicken problems. The switch drivers
all are standard mdio_module_driver, module_platform_driver,
module_i2c_driver, module_pci_driver. Nothing special here. Things
load in whatever order they load, and it all works out, maybe with an
EPROBE_DEFER cycle. Which is good, we get our error paths tested, and
sometimes find bugs that way.

     Andrew