linux-kernel - Re: [PATCH v8 10/10] arm64: dts: rockchip: rk3399-evb-ind: Add support for DisplayPort

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Message-ID: <7853bbf0-34e5-4880-a2f4-2d73f25cd5e6@rock-chips.com>
Date: Thu, 30 Oct 2025 11:13:51 +0800
From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
To: Peter Chen <hzpeterchen@...il.com>, Chaoyi Chen <kernel@...kyi.com>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Vinod Koul <vkoul@...nel.org>,
 Kishon Vijay Abraham I <kishon@...nel.org>, Heiko Stuebner
 <heiko@...ech.de>, Sandy Huang <hjc@...k-chips.com>,
 Andy Yan <andy.yan@...k-chips.com>,
 Yubing Zhang <yubing.zhang@...k-chips.com>,
 Frank Wang <frank.wang@...k-chips.com>,
 Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Amit Sunil Dhamne <amitsd@...gle.com>, Dragan Simic <dsimic@...jaro.org>,
 Johan Jonker <jbx6244@...il.com>, Diederik de Haas <didi.debian@...ow.org>,
 Peter Robinson <pbrobinson@...il.com>, linux-usb@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-phy@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v8 10/10] arm64: dts: rockchip: rk3399-evb-ind: Add
 support for DisplayPort

On 10/30/2025 10:50 AM, Peter Chen wrote:

>>> Okay.  My question is basic: USB2 PHY supplies DP/DM, and the DP/DM is
>>> short for Type-C connector,
>>> and no control is needed for Type-C application.
>>> Why is there a remote-endpoint connection between USB2 PHY and Type-C connector?
>>   From the perspective of Type-C, this should not be added.  Is the approach in v2 correct [0] ?
>>
> Have you tried debugging based on upstream code?

Yes, I have tried both the v2 and v8 approaches, and both can work.


> v2 is correct, but the dts needs to improve.
> - There is a remote-endpoint connection for USB role switch between
> Type-C connector
> device and USB controller device
> - There is a remote-endpoint connection for orientation and lane configuration
> between Type-C connector device and USB/DP PHY device.

In v8 patch5, we implemented typec_mux and typec_switch in the USB/DP PHY.

I think the current remote-endpoint connections are all child node of the USB/DP PHY. That is:


&tcphy0_dp {
     mode-switch;
     ...
};


&tcphy0_usb3 {
     orientation-switch;
     ...
};


Does this still need to be improved? Thank you.


>
> Peter
>
>> [0]: https://lore.kernel.org/all/20250715112456.101-6-kernel@airkyi.com/
>>
>> Or is the following approach correct?
>>
>>
>> port@0 {
>>       reg = <0>;
>>
>>       usbc_hs: endpoint {
>>           remote-endpoint = <&tcphy0>;
>>       };
>> };
>>
>> port@1 {
>>       reg = <1>;
>>
>>       usbc_ss: endpoint {
>>           remote-endpoint = <&tcphy0>;
>>       };
>> };
>>
>> port@2 {
>>       reg = <2>;
>>
>>       usbc_dp: endpoint {
>>           remote-endpoint = <&tcphy0_typec_dp>;
>>       };
>> };
>>
>>
>>>>>>> +                               port@1 {
>>>>>>> +                                       reg = <1>;
>>>>>>> +
>>>>>>> +                                       usbc_ss: endpoint {
>>>>>>> + remote-endpoint = <&tcphy0_typec_ss>;
>>>>>>> +                                       };
>>>>>>> +                               };
>>>>>>> +
>>>>>>> +                               port@2 {
>>>>>>> +                                       reg = <2>;
>>>>>>> +
>>>>>>> +                                       usbc_dp: endpoint {
>>>>>>> + remote-endpoint = <&tcphy0_typec_dp>;
>>>>>>> +                                       };
>>>>>>> +                               };
>>>>>>> +                       };
>>>>>>> +               };
>>>>>>> +       };
>>>>>>> +};
>>>>>>> +
>>>>>> .....
>>>>>>>     &u2phy0 {
>>>>>>>            status = "okay";
>>>>>>> +
>>>>>>> +       port {
>>>>>>> +               u2phy0_typec_hs: endpoint {
>>>>>>> +                       remote-endpoint = <&usbc_hs>;
>>>>>>> +               };
>>>>>>> +       };
>>>>>>>     };
>>>>>>>
>>>>>> There is no switch and mux, how to co-work with Type-C?
>>>>> I checked the phy-rockchip-inno-usb2.c but did not find any switch or mux. Does this mean that we need to implement them? Thank you.
>>>> Wait a minute, actually we have multiple hardware interfaces, one of which is Type-C, eventually connected to USBDPPHY, and the other is micro-usb connected to U2PHY.
>>> I assume the Micro-USB connector does not use Type-C/PD IC, is it
>>> right? Does it relate to this patch?
>>>
>>> Best regards,
>>> Peter
>>>
>
-- 
Best,
Chaoyi