Re: [PATCH 02/16] dt-bindings: spi: Add bcmbca-hsspi controller support

William Zhang <william.zhang@xxxxxxxxxxxx> · Wed, 11 Jan 2023 10:04:16 -0800

On 01/11/2023 01:02 AM, Krzysztof Kozlowski wrote:
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

As I mentioned in another email,  I would be okay to use these 
compatibles to differentiate by ip rev and to conforms to brcm convention:
"brcm,bcmXYZ-hsspi", "brcm,bcmbca-hsspi-v1.0", "brcm,bcmbca-hsspi";
"brcm,bcmXYZ-hsspi", "brcm,bcmbca-hsspi-v1.1", "brcm,bcmbca-hsspi";

In the two drivers I included in this series, it will be bound to 
brcm,bcmbca-hsspi-v1.0 (in additional to brcm,bcm6328-hsspi) and 
brcm,bcmbca-hsspi-v1.1 respectively.  This way we don't need to update 
the driver with a new soc specific compatible whenever a new chips comes 
out.

Does this sound good to you?
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