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Message-ID: <71c2e796-f0fb-90cd-4599-13c9718f41d5@linaro.org>
Date:   Wed, 11 Jan 2023 10:02:50 +0100
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Subject: Re: [PATCH 02/16] dt-bindings: spi: Add bcmbca-hsspi controller
 support
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To:     Florian Fainelli <f.fainelli@gmail.com>,
        William Zhang <william.zhang@broadcom.com>,
        Linux SPI List <linux-spi@vger.kernel.org>,
        Broadcom Kernel List <bcm-kernel-feedback-list@broadcom.com>
Cc:     anand.gore@broadcom.com, tomer.yacoby@broadcom.com,
        dan.beygelman@broadcom.com, joel.peshkin@broadcom.com,
        jonas.gorski@gmail.com, kursad.oney@broadcom.com, dregan@mail.com,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Mark Brown <broonie@kernel.org>,
        Rob Herring <robh+dt@kernel.org>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20230106200809.330769-1-william.zhang@broadcom.com>
 <20230106200809.330769-3-william.zhang@broadcom.com>
 <b529a53b-d00c-063d-a58d-e64b0300605d@linaro.org>
 <5dfac2d7-3b4b-9ded-0dde-26b289c604d0@broadcom.com>
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 <32a464f8-6a4b-6777-9775-f17e990e0c6a@gmail.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <32a464f8-6a4b-6777-9775-f17e990e0c6a@gmail.com>
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On 10/01/2023 23:18, Florian Fainelli wrote:
> On 1/10/23 00:40, Krzysztof Kozlowski wrote:
>>>> No, it is discouraged in such forms. Family or IP block compatibles
>>>> should be prepended with a specific compatible. There were many issues
>>>> when people insisted on generic or family compatibles...
>>>>
>>>>> Otherwise we will have to have a compatible string with chip model for
>>>>> each SoC even they share the same IP. We already have more than ten of
>>>>> SoCs and the list will increase.  I don't see this is a good solution too.
>>>>
>>>> You will have to do it anyway even with generic fallback, so I don't get
>>>> what is here to gain... I also don't get why Broadcom should be here
>>>> special, different than others. Why it is not a good solution for
>>>> Broadcom SoCs but it is for others?
>>>>
>>> I saw a few other vendors like these qcom ones:
>>>    qcom,spi-qup.yaml
>>>        - qcom,spi-qup-v1.1.1 # for 8660, 8960 and 8064
>>>        - qcom,spi-qup-v2.1.1 # for 8974 and later
>>>        - qcom,spi-qup-v2.2.1 # for 8974 v2 and later
>>>    qcom,spi-qup.yaml
>>>        const: qcom,geni-spi
>>
>> IP block version numbers are allowed when there is clear mapping between
>> version and SoCs using it. This is the case for Qualcomm because there
>> is such clear mapping documented and available for Qualcomm engineers
>> and also some of us (although not public).
>>
>>> I guess when individual who only has one particular board/chip and is
>>> not aware of the IP family,  it is understandable to use the chip
>>> specific compatible string.
>>
>> Family of devices is not a versioned IP block.
> 
> Would it be acceptable to define for instance:
> 
> - compatible = "brcm,bcm6868-hsspi", "brcm,bcmbca-hsspi";

Yes, this is perfectly valid. Although it does not solve William
concerns because it requires defining specific compatibles for all of
the SoCs.

Best regards,
Krzysztof