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Date: Tue, 11 Jun 2024 14:28:04 +0200
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Subject: Re: [PATCH] arm64: dts: mt7622: fix switch probe on bananapi-r64
To: =?UTF-8?B?QXLEsW7DpyDDnE5BTA==?= <arinc.unal@arinc9.com>,
 Thorsten Leemhuis <regressions@leemhuis.info>, Rob Herring
 <robh@kernel.org>, Conor Dooley <conor+dt@kernel.org>,
 Krzysztof Kozlowski <krzk+dt@kernel.org>,
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Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
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 Daniel Golle <daniel@makrotopia.org>, frank-w@public-files.de,
 Linux regressions mailing list <regressions@lists.linux.dev>,
 Frank Wunderlich <linux@fw-web.de>, Paolo Abeni <pabeni@redhat.com>
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From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
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Il 11/06/24 13:38, Arınç ÜNAL ha scritto:
> On 11/06/2024 14:30, Thorsten Leemhuis wrote:
>> On 07.06.24 16:15, Thorsten Leemhuis wrote:
>>> On 07.06.24 16:03, Paolo Abeni wrote:
>>>> On Thu, 2024-06-06 at 10:26 +0200, Thorsten Leemhuis wrote:
>>>>> On 31.05.24 08:10, Arınç ÜNAL wrote:
>>>>>> On 31/05/2024 08.40, Thorsten Leemhuis wrote:
>>>>>>> [adding Paolo, who committed the culprit]
>>>>>
>>>>> /me slowly wonders if the culprit should be reverted for now (see below)
>>>>> and should be reapplied later together with the matching changes from
>>>>> Arınç ÜNAL.
>>>>
>>>> FWIS I think a revert should be avoided, given that a fix is available
>>>> and nicely small.
>>>
>>> Yeah, on one hand I agree; but on the other it seems that the
>>> maintainers that would have to take care of the dt changes to fix this
>>> until now remained silent in this thread, apart from Rob who sent the
>>> mail regarding the warnings.
>>>
>>> I put those maintainers in the To: field of this mail, maybe that might
>>> lead to some reaction.
>>
>> Still no reply from the DRS folks or any other progress I noticed. Guess
>> that means I will soon have no other choice than to get Linus involved,
>> as this looks stuck. :-( #sigh
> 
> Does it have to be Linus that needs to apply "[PATCH 0/2] Set PHY address
> of MT7531 switch to 0x1f on MediaTek arm64 boards"? Aren't there any other
> ARM maintainers that can apply the fix to their tree?
> 
> Arınç

You have feedback from two people on the series that you mentioned, and noone
is going to apply something that needs to be fixed.

I'm giving you the possibility of addressing the comments in your patch, but
I don't want to see any mention of the driver previously ignoring this or that
as this is irrelevant for a hardware description. Devicetree only describes HW.

Adding up, in commit 868ff5f4944a ("net: dsa: mt7530-mdio: read PHY address of 
switch from device tree"),
you have created a regression.

Regressions should be fixed - as in - if the driver did work before with the old
devicetrees, it shall still work. You can't break ABI. Any changes that you do
to your driver must not break functionality with old devicetrees.

So...

------> Fix the driver that you broke <------

After you've fixed it - and I repeat - only after, *and* after someone (Frank?)
validates that the old devicetrees do work with the fixed driver, I will take
the device tree fixes for that MDIO address (as those are, again, fixing a
description of the hardware on those boards, so I agree that those must be fixed
AS WELL).


Regards,
Angelo