linux-kernel - Re: [PATCH 2/9] dt-bindings: phy: qcom,m31: Document qcom,m31 USB phy

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Message-ID: <aca54f67-cc09-ff4f-93ca-6973d153db2c@linaro.org>
Date:   Sat, 17 Jun 2023 10:48:41 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Varadarajan Narayanan <quic_varada@...cinc.com>
Cc:     agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        vkoul@...nel.org, kishon@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        gregkh@...uxfoundation.org, catalin.marinas@....com,
        will@...nel.org, mturquette@...libre.com, sboyd@...nel.org,
        p.zabel@...gutronix.de, arnd@...db.de, geert+renesas@...der.be,
        neil.armstrong@...aro.org, nfraprado@...labora.com,
        broonie@...nel.org, rafal@...ecki.pl, quic_srichara@...cinc.com,
        quic_varada@...cinc.org, quic_wcheng@...cinc.com,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH 2/9] dt-bindings: phy: qcom,m31: Document qcom,m31 USB phy

On 15/06/2023 07:27, Varadarajan Narayanan wrote:
>>> +          - enum:
>>> +              - qcom,m31-usb-hsphy
>>
>> I am confused what's this. If m31 is coming from some IP block provider,
>> then you are using wrong vendor prefix.
>> https://www.m31tech.com/download_file/M31_USB.pdf
>>
>>
>>> +              - qcom,ipq5332-m31-usb-hsphy
>>
>> This confuses me even more. IPQ m31?
> 
> Will change this to m31,usb-hsphy and m31,ipq5332-usb-hsphy respectively.
> Will that be acceptable?

m31,ipq5332 seems wrong, as m31 did not create ipq5332. Does the m31
device have some name/version/model? If it is not really known, then I
would just propose to go with qcom,ipq5332-usb-hsphy.

Skip generic compatible ("usb-hsphy") entirely.

And then we have... existing bindings qcom,usb-hs-phy.yaml. Don't create
something similar with difference in the hyphen. Just use device
specific compatible thus device specific filename.

> 
>>> +
>>> +  reg:
>>> +    description:
>>> +      Offset and length of the M31 PHY register set
>>
>> Drop description, obvious.
> 
> Ok.
> 
>>> +    maxItems: 2
>>> +
>>> +  reg-names:
>>> +    items:
>>> +      - const: m31usb_phy_base
>>> +      - const: qscratch_base
>>
>> Drop "_base" from both.
> 
> Ok. Will drop qscratch_base. This is in the controller space.
> Should not come here.

Then drop reg-names entirely.

> 
>>> +
>>> +  phy_type:
>>> +    oneOf:
>>> +      - items:
>>> +          - enum:
>>> +              - utmi
>>> +              - ulpi
>>
>> This does not belong to phy, but to USB node.
> 
> This is used by the driver to set a bit during phy init. Hence
> have it as a replication of the USB node's entry. If this is not
> permissible, is there some way to get this from the USB node,
> or any other alternative mechanism?

Shouldn't USB controller choose what type of PHY type it wants?

> 
>>> +
>>> +additionalProperties: false
>>> +
>>> +examples:
>>> +  - |
>>> +    #include <dt-bindings/clock/qcom,ipq5332-gcc.h>
>>> +    hs_m31phy_0: hs_m31phy@...0 {
>>
>> Node names should be generic. See also explanation and list of examples
>> in DT specification:
>> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
>>
>> Also, no underscores in node names.
> 
> Will change this as usbphy0:hs_m31phy@...00

This does not solve my comments. I did not write "label" but "node name".

Best regards,
Krzysztof