PROBLEM: Broken or delayed ethernet on Xilinx ZCU104 since 5.18 (regression)

[Nick Bowler]

On 2023-08-04, Rob Herring <robh at kernel.org> wrote:
> On Fri, Aug 4, 2023 at 11:52 AM Nick Bowler <nbowler at draconx.ca> wrote:
>> I don't know about the deferred probe timeout, but I bisected the 6.5-rc4
>> breakage to this commit:
>>
>>   commit c720a1f5e6ee8cb39c28435efc0819cec84d6ee2
>>   Author: Michal Simek <michal.simek at amd.com>
>>   Date:   Mon May 22 16:59:48 2023 +0200
>>
>>       arm64: zynqmp: Describe TI phy as ethernet-phy-id
>
> I don't see anything obviously problematic with that commit. (The
> #phy-cells property added is wrong as ethernet phys don't use the phy
> binding, but that should just be ignored). I'd check if the phy probed
> and has a DT node associated with it.

I think the answer is "no, the phy was not probed".  Without reverting
that commit, there is absolutely nothing in /sys/bus/mdio_bus/devices.
There is no phy device link under /sys/bus/mdio_bus/drivers/"TI DP83867",
and there is no mdio_bus under /sys/bus/platform/devices/ff0e0000.ethernet.

When I revert that commit, I can locate the phy device under all these
locations.

> fw_devlink tracks parent-child dependencies and maybe changing to
> parent-grandchild affected that. We don't yet track 'phy-handle'
> dependencies, but we'd have a circular one here if we did (though that
> should be handled). Does "fw_devlink=off" help?

Booting with fw_devlink=off results in no obvious change in behaviour.

Thanks,
  Nick