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Date:   Thu, 14 Apr 2022 09:32:56 +0200
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Subject: Re: [PATCH v2 1/2] dt-bindings: dwc2: Add bindings for new Ingenic
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To:     "H. Nikolaus Schaller" <hns@goldelico.com>,
        Zhou Yanjie <zhouyanjie@wanyeetech.com>,
        Krzysztof Kozlowski <krzk+dt@kernel.org>
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        linux-usb@vger.kernel.org, linux-mips <linux-mips@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS 
        <devicetree@vger.kernel.org>, dragancecavac@yahoo.com,
        dongsheng.qiu@ingenic.com, qipengzhen <aric.pzqi@ingenic.com>,
        rick.tyliu@ingenic.com, sernia.zhou@foxmail.com,
        zhenwenjin@gmail.com, reimu@sudomaker.com
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From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
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On 13/04/2022 21:30, H. Nikolaus Schaller wrote:
> So we need "snps,dwc2" to get any driver match and I thought the "ingenic,jz4780-otg" is redundant.
> 
> But maintainers convinced me to keep it as a dummy compatible in the .dtsi for potential future
> specialization (which does not exist and seems not to be necessary). 

Isn't exactly the next patch 2/2 using such specialization?

> Unless I can convince them 
> that this is never ever needed. Which is beyond my knowledge and almost everyone.
> 
> So we can't remove the "snps,dwc2" here.
> 
> Well, we can with more work elsewhere.
> You have to extend the dwc2_of_match_table to include all ingenic devices.
> 
> Therefore we now know 3 potential solutions:
> a) remove "ingenic,jz4780-otg" from jz4780.dtsi (my proposal)
> b) add "ingenic,jz4780-otg" to dwc2.yaml together with "snps,dwc2" (your proposal + my suggestion here)
> c) add only "ingenic,jz4780-otg" to dwc2.yaml and extend the match table in drivers//usb/dwc2/params.c (new proposals)
> 
> From consistency point of view I think variant b) is the right one. a) was rejected and c) only adds redundant code.

c) was already proposed by Zhou, so if you think the code is not correct
(the params for jz4780) maybe nack it there, so we will know that driver
needs fixes.

Best regards,
Krzysztof