Re: fwnode_for_each_child_node() and OF backend discrepancy

Michael Walle
2022-06-28T13:27:12Z

>> I was trying to fix the lan966x driver [1] which doesn't work if there
>> are disabled nodes in between.
>
> Can you elaborate what's wrong now in the behaviour of the driver? In
> the code it uses twice the _available variant.

Imagine the following device tree snippet:
port0 {
reg = <0>;
status = "okay";
}
port1 {
reg = <1>;
status = "disabled";
}
port@2 {
reg = <2>;
status = "okay";
}

The driver will set num_phys_ports to 2. When port@2 is probed, it
will have the (correct!) physical port number 2. That will then
trigger various EINVAL checks with "port_num >= num_phys_ports" or
WARN()s.

So the easiest fix would be to actual count all the child nodes
(regardless if they are available or not), assuming there are as
many nodes as physical ports.

But num_phys_ports being a property of the hardware I don't
think it's good to deduce it by counting the child nodes anyway,
but it should rather be a (hardcoded) property of the driver.

-michael

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