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Message-ID: <d26c7ebd-fc1a-391e-39e4-5ec41bf4fbfa@linaro.org>
Date:   Fri, 20 May 2022 15:38:36 +0200
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Subject: Re: [PATCH 2/3] dt-bindings: usb: atmel: Add Microchip LAN966x
 compatible string
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To:     Herve Codina <herve.codina@bootlin.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Nicolas Ferre <nicolas.ferre@microchip.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Claudiu Beznea <claudiu.beznea@microchip.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Horatiu Vultur <horatiu.vultur@microchip.com>,
        linux-usb@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-clk@vger.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>
References: <20220513105850.310375-1-herve.codina@bootlin.com>
 <20220513105850.310375-3-herve.codina@bootlin.com>
 <8f0d4127-7e66-cf50-21c9-99680f737e30@linaro.org>
 <20220520133426.3b4728ae@bootlin.com>
 <b087c34f-0e2f-edd0-a738-3ffc2853a41b@linaro.org>
 <20220520142109.57b84da2@bootlin.com>
 <01b31a02-523e-10bf-3b46-5b830e456522@linaro.org>
 <20220520150243.625723fa@bootlin.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <20220520150243.625723fa@bootlin.com>
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On 20/05/2022 15:02, Herve Codina wrote:
> On Fri, 20 May 2022 14:50:24 +0200
> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:
> 
>> On 20/05/2022 14:21, Herve Codina wrote:
>>>>> I think it makes sense to keep 'microchip,lan966x-udc' for the USB
>>>>> device controller (same controller on LAN9662 and LAN9668) and so
>>>>> keeping the same rules as for other common parts.    
>>>>
>>>> Having wildcard was rather a mistake and we already started correcting
>>>> it, so keeping the "mistake" neither gives you consistency, nor
>>>> correctness...
>>>>  
>>>
>>> I think that the "family" compatible should be present.
>>> This one allows to define the common parts in the common
>>> .dtsi file (lan966x.dtsi in our case).
>>>
>>> What do you think about:
>>> - microchip,lan9662-udc
>>> - microchip,lan9668-udc
>>> - microchip,lan966-udc  <-- Family
>>>
>>> lan966 is defined as the family compatible string since (1) in
>>> bindings/arm/atmel-at91.yaml and in Documentation/arm/microchip.rst
>>>   
>>
>> You can add some family compatible, if it makes sense. I don't get why
>> do you mention it - we did not discuss family names, but using
>> wildcards... Just please do not add wildcards.
> 
> Well, I mentioned it as I will only use the family compatible string
> and not the SOC (lan9662 or lan9668) compatible string in lan966x.dtsi.
> In this case, the family compatible string can be seen as a kind of
> "wildcard".

I understood as "the "family" compatible should be present" as you want
to add it as a fallback. It would be okay (assuming devices indeed share
family design). If you want to use it as the only one, then it is again
not a recommended approach. Please use specific compatibles.

I mean, why do we have this discussion? What is the benefit for you to
implement something not-recommended by Devicetree spec and style?

Best regards,
Krzysztof