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From:   Nick Bowler <nbowler@draconx.ca>
Date:   Fri, 4 Aug 2023 17:31:21 -0400
Message-ID: <CADyTPEwY4ydUKGtGNayf+iQSqRVBQncLiv0TpO9QivBVrmOc4g@mail.gmail.com>
Subject: Re: PROBLEM: Broken or delayed ethernet on Xilinx ZCU104 since 5.18 (regression)
To:     Rob Herring <robh@kernel.org>
Cc:     Saravana Kannan <saravanak@google.com>,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        netdev@vger.kernel.org, regressions@lists.linux.dev
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On 2023-08-04, Rob Herring <robh@kernel.org> wrote:
> On Fri, Aug 4, 2023 at 11:52=E2=80=AFAM Nick Bowler <nbowler@draconx.ca> =
wrote:
>> I don't know about the deferred probe timeout, but I bisected the 6.5-rc=
4
>> breakage to this commit:
>>
>>   commit c720a1f5e6ee8cb39c28435efc0819cec84d6ee2
>>   Author: Michal Simek <michal.simek@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=3Doff" help?

Booting with fw_devlink=3Doff results in no obvious change in behaviour.

Thanks,
  Nick