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From:   Nick Bowler <nbowler@draconx.ca>
Date:   Fri, 4 Aug 2023 12:54:40 -0400
Message-ID: <CADyTPExgjcaUeKiR108geQhr0KwFC0A8qa_n_ST2RxhbSczomQ@mail.gmail.com>
Subject: Re: PROBLEM: Broken or delayed ethernet on Xilinx ZCU104 since 5.18 (regression)
To:     Rob Herring <robh@kernel.org>
Cc:     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, Nick Bowler <nbowler@draconx.ca> wrote:
> On 04/08/2023, Rob Herring <robh@kernel.org> wrote:
>> On Fri, Aug 4, 2023 at 9:27=E2=80=AFAM Nick Bowler <nbowler@draconx.ca> =
wrote:
>>>   commit e461bd6f43f4e568f7436a8b6bc21c4ce6914c36
>>>   Author: Robert Hancock <robert.hancock@calian.com>
>>>   Date:   Thu Jan 27 10:37:36 2022 -0600
>>>
>>>       arm64: dts: zynqmp: Added GEM reset definitions
>>>
>>> Reverting this fixes the problem on 5.18.  Reverting this fixes the
>>> problem on 6.1.  Reverting this fixes the problem on 6.4.  In all of
>>> these versions, with this change reverted, the network device appears
>>> without delay.
>>
>> With the above change, the kernel is going to be waiting for the reset
>> driver which either didn't exist or wasn't enabled in your config
>> (maybe kconfig needs to be tweaked to enable it automatically).
>
> The dts defines a reset-controller node with
>
>   compatible =3D "xlnx,zynqmp-reset"
>
> As far as I can see, this is supposed to be handled by the code in
> drivers/reset/zynqmp-reset.c driver, it is enabled by CONFIG_ARCH_ZYNQMP,
> and I have that set to "y", and it appears to be getting compiled in (tha=
t
> is, there is a drivers/reset/zynqmp-reset.o file in the build directory).

Oh, I get it, to include this driver I need to also enable:

  CONFIG_RESET_CONTROLLER=3Dy

Setting this fixes 6.4.  Perhaps CONFIG_ARCH_ZYNQMP should select it?
I guess the reset-zynqmp.o file that was in my build directory must
have been leftover garbage from a long time ago.

However, even with this option enabled, 6.5-rc4 remains broken (no
change in behaviour wrt. the network device).  I will bisect this
now.

Cheers,
  Nick