linux-kernel - Re: [PATCH 1/7] dt-bindings: phy: qcom,sc8280xp-qmp-usb43dp: Add ports and orientation-switch

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Date:   Thu, 4 May 2023 15:50:53 +0200
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Bjorn Andersson <quic_bjorande@...cinc.com>,
        Bryan O'Donoghue <pure.logic@...us-software.ie>
Cc:     Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Johan Hovold <johan@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] dt-bindings: phy: qcom,sc8280xp-qmp-usb43dp: Add
 ports and orientation-switch

On 27/04/2023 21:52, Bjorn Andersson wrote:
> On Wed, Apr 26, 2023 at 11:21:29AM +0100, Bryan O'Donoghue wrote:
>> On Tue, Apr 25, 2023 at 4:40 AM Bjorn Andersson
>> <quic_bjorande@...cinc.com> wrote:
>>>
>>> The QMP combo phy can be connected to a TCPM, a USB controller and a
>>> DisplayPort controller for handling USB Type-C orientation switching
>>> and propagating HPD signals.
>>>
>>> Extend the binding to allow these connections to be described.
>>>
>>> Signed-off-by: Bjorn Andersson <quic_bjorande@...cinc.com>
>>> ---
>>>   .../phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml    | 51 +++++++++++++++++++
>>>   1 file changed, 51 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml b/Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml
>>> index 3cd5fc3e8fab..c037ac90ce7f 100644
>>> --- a/Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml
>>> +++ b/Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml
>>> @@ -60,6 +60,26 @@ properties:
>>>       description:
>>>         See include/dt-bindings/dt-bindings/phy/phy-qcom-qmp.h
>>>
>>> +  orientation-switch:
>>> +    description:
>>> +      Flag the PHY as possible handler of USB Type-C orientation switching
>>> +    type: boolean
>>> +
>>> +  ports:
>>> +    $ref: /schemas/graph.yaml#/properties/ports
>>> +    properties:
>>> +      port@0:
>>> +        $ref: /schemas/graph.yaml#/properties/port
>>> +        description: Output endpoint of the PHY
>>> +
>>> +      port@1:
>>> +        $ref: /schemas/graph.yaml#/$defs/port-base
>>> +        description: Incoming endpoint from the USB controller
>>
>> Do you really need this one ?
>>
>> The controller doesn't process orientation switching.
>>
> 
> I don't have a need for it, as we can deal with role switching by
> connecting connector/port@0 to the dwc3.
> 
> But if we ever have a need to describe the dwc3 -> QMP -> connector path
> in the of_graph I think it would look prettier to have USB input as
> port@1 and DP input as port@....

I think it would be great to have port@1 for USB SS and port@2 for DP,
otherwise we need to add 2 endpoints as I sent in
https://lore.kernel.org/all/20230503-topic-sm8450-graphics-dp-next-v1-1-d1ee9397f2a6@linaro.org/
since we split USB HS and SS streams on SM8[345]50 platforms.

> 
> Do you have a concern with keeping it around in the DT (the
> implementation doesn't need to care)?
> 
> Regards,
> Bjorn