Message-ID: <a9acd3b4-2b03-86c0-711c-a3840aeab574@arinc9.com>
Date:   Thu, 2 Mar 2023 12:17:46 +0300
From:   Arınç ÜNAL <arinc.unal@...nc9.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Rob Herring <robh@...nel.org>
Cc:     Sergio Paracuellos <sergio.paracuellos@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-mediatek@...ts.infradead.org, linux-mips@...r.kernel.org,
        linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Matthias Brugger <matthias.bgg@...il.com>,
        Sean Wang <sean.wang@...nel.org>,
        William Dean <williamsukatube@...il.com>,
        Daniel Golle <daniel@...rotopia.org>,
        Daniel Santos <daniel.santos@...ox.com>,
        Luiz Angelo Daros de Luca <luizluca@...il.com>,
        Frank Wunderlich <frank-w@...lic-files.de>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Sean Wang <sean.wang@...iatek.com>, erkin.bozoglu@...ont.com
Subject: Re: [RFC PATCH 07/16] dt-bindings: pinctrl: ralink: add new
 compatible strings

On 2.03.2023 11:28, Krzysztof Kozlowski wrote:
> On 01/03/2023 09:15, Arınç ÜNAL wrote:
>> On 1.03.2023 05:44, Rob Herring wrote:
>>> On Tue, Feb 28, 2023 at 07:46:36PM +0300, Arınç ÜNAL wrote:
>>>> On 27/02/2023 20:33, Rob Herring wrote:
>>>>> On Wed, Feb 22, 2023 at 09:39:23PM +0300, arinc9.unal@...il.com wrote:
>>>>>> From: Arınç ÜNAL <arinc.unal@...nc9.com>
>>>>>>
>>>>>> Add the ralink,rt2880-pinmux compatible string. It had been removed from
>>>>>> the driver which broke the ABI.
>>>>>>
>>>>>> Add the mediatek compatible strings. Change the compatible string on the
>>>>>> examples with the mediatek compatible strings.
>>>>>>
>>>>>> Signed-off-by: Arınç ÜNAL <arinc.unal@...nc9.com>
>>>>>> ---
>>>>>>     .../devicetree/bindings/pinctrl/ralink,mt7620-pinctrl.yaml | 7 +++++--
>>>>>>     .../devicetree/bindings/pinctrl/ralink,mt7621-pinctrl.yaml | 7 +++++--
>>>>>>     .../devicetree/bindings/pinctrl/ralink,rt2880-pinctrl.yaml | 7 +++++--
>>>>>>     .../devicetree/bindings/pinctrl/ralink,rt305x-pinctrl.yaml | 7 +++++--
>>>>>>     .../devicetree/bindings/pinctrl/ralink,rt3883-pinctrl.yaml | 7 +++++--
>>>>>>     5 files changed, 25 insertions(+), 10 deletions(-)
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/pinctrl/ralink,mt7620-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/ralink,mt7620-pinctrl.yaml
>>>>>> index 1e63ea34146a..531b5f616c3d 100644
>>>>>> --- a/Documentation/devicetree/bindings/pinctrl/ralink,mt7620-pinctrl.yaml
>>>>>> +++ b/Documentation/devicetree/bindings/pinctrl/ralink,mt7620-pinctrl.yaml
>>>>>> @@ -17,7 +17,10 @@ description:
>>>>>>     properties:
>>>>>>       compatible:
>>>>>> -    const: ralink,mt7620-pinctrl
>>>>>> +    enum:
>>>>>> +      - mediatek,mt7620-pinctrl
>>>>>> +      - ralink,mt7620-pinctrl
>>>>>
>>>>> We don't update compatible strings based on acquistions nor marketing
>>>>> whims. If you want to use 'mediatek' for new things, then fine.
>>>>
>>>> Understood. Only the SoCs with rtXXXX were rebranded, the mtXXXX SoCs share
>>>> the same architecture from Ralink, so they were incorrectly called Ralink
>>>> SoCs.
>>>>
>>>> I can remove the new strings from Ralink SoCs and add them only for MediaTek
>>>> SoCs. Or you could make an exception for this one, regarding the situation.
>>>> Whatever you think is best.
>>>
>>> I'm not in a position to make an exception as I know little about this
>>> platform. Carrying both strings is a NAK. Either you (and everyone using
>>> these platforms) care about the ABI and are stuck with the "wrong"
>>> string. In the end, they are just unique identifiers. Or you don't care
>>> and break the ABI and rename everything. If you do that, do just that in
>>> your patches and make it crystal clear in the commit msg that is your
>>> intention and why that is okay.
>>
>> Ralink had their MIPS SoCs pre-acquisition, RT2880, etc. MediaTek
>> introduced new SoCs post-acquisition, MT7620, MT7621, MT7628, and
>> MT7688, utilising the same platform from Ralink, sharing the same
>> architecture code, pinctrl core driver, etc.
>>
>> I don't intend to break the ABI at all. On the contrary, I fix it where
>> possible.
>>
>> If I understand correctly, from this conversation and what Krzysztof
>> said, all strings must be kept on the schemas so I can do what I said on
>> the composed mail. Only match the pin muxing information on the strings
>> that won't match multiple pin muxing information from other schemas.
>>
>> This way we don't break the ABI, introduce new compatible strings while
>> keeping the remaining ones, and make schemas match correctly.
>>
>> Let me know if this is acceptable to you.
> 
> If by "introduce new compatible strings" you mean duplicate compatibles
> to fix the ralink->mediatek, then you ignored entire email from Rob -
> this and previous. We don't do this. Leave them as is.
> 
> If you meant something else, explain more...

Let me put them in a group to better explain.

## Fix ABI

ralink,rt2880-pinmux was there before, it was removed which broke the 
ABI. I'm reintroducing it to fix it.

## New strings to be able to split bindings

New strings are needed for MT7628/MT7688 and some RT SoCs to be able to 
properly document the pin muxing information.

## Incorrect naming

MT7620, MT7621, MT7628, and MT7688 SoCs are incorrectly called Ralink, 
introduce new ralink->mediatek compatible strings to address it.

## Exception for RT SoCs to be called MediaTek

This is where I was asking an exception to be made. Rob told us here 
they know little about the platform so I explained it.

MediaTek acquired Ralink and then introduced new MediaTek SoCs utilising 
the same platform from Ralink.

Anyway, now that I look at this again, it makes sense to me as well not 
to rename the Ralink SoCs. I'll call the RT SoCs Ralink on the kconfig, 
pinctrl driver, and dt-binding schemas on my next version.

Arınç

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