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 10:54 AM Nick Bowler <nbowler at draconx.ca> wrote:
>> Oh, I get it, to include this driver I need to also enable:
>>
>>   CONFIG_RESET_CONTROLLER=y
>>
>> Setting this fixes 6.4.  Perhaps CONFIG_ARCH_ZYNQMP should select it?
>
> Maybe. Do other platforms do that?

Of the ~40 platforms in arch/arm64/Kconfig.platforms, there appear to
be 5 that do select it.

>> However, even with this option enabled, 6.5-rc4 remains broken (no
>> change in behaviour wrt. the network device).  I will bisect this
>> now.
>
> It would be good to know why the deferred probe timeout doesn't work.
> If you disable modules, the kernel shouldn't wait past late_initcall.
> Though this functionality keeps getting tweaked, so I may be off on
> the current behavior.

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

So, reverting that on master appears to correct the issue (together with
setting CONFIG_RESET_CONTROLLER=y).