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

From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
To: Varadarajan Narayanan <quic_varada@quicinc.com>
Cc: agross@kernel.org, andersson@kernel.org,
	konrad.dybcio@linaro.org, vkoul@kernel.org, kishon@kernel.org,
	robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
	conor+dt@kernel.org, gregkh@linuxfoundation.org,
	catalin.marinas@arm.com, will@kernel.org,
	mturquette@baylibre.com, sboyd@kernel.org,
	p.zabel@pengutronix.de, arnd@arndb.de, geert+renesas@glider.be,
	neil.armstrong@linaro.org, nfraprado@collabora.com,
	broonie@kernel.org, rafal@milecki.pl, quic_srichara@quicinc.com,
	quic_varada@quicinc.org, quic_wcheng@quicinc.com,
	linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-clk@vger.kernel.org
Subject: Re: [PATCH 2/9] dt-bindings: phy: qcom,m31: Document qcom,m31 USB phy
Date: Sat, 17 Jun 2023 10:48:41 +0200	[thread overview]
Message-ID: <aca54f67-cc09-ff4f-93ca-6973d153db2c@linaro.org> (raw)
In-Reply-To: <20230615052746.GB22186@varda-linux.qualcomm.com>

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@5b00 {
>>
>> 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@7b000

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

Best regards,
Krzysztof