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

From: Chaoyi Chen

Date: Thu Oct 30 2025 - 02:50:45 EST

On 10/30/2025 2:13 PM, Peter Chen wrote:

On Thu, Oct 30, 2025 at 11:14 AM Chaoyi Chen <chaoyi.chen@xxxxxxxxxxxxxx> wrote:

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.

Hi Chaoyi,

There are two questions I have still not seen the answer to:
- Why USB2 PHY is related to your Type-C patch?

I was just following other people's approach. Sorry, this should be removed from the dts.

- How does the USB role switch event notify the USB controller driver, eg dwc3?

Sorry, I misunderstood what you said before. There is indeed a missing usb-role-switch now. I referred to the approach in rk3588-evb1-v10.dts. Is the following way of writing correct?

&usbc_connector {
ports {
#address-cells = <1>;
#size-cells = <0>;

port@0 {
reg = <0>;

usbc_orien_sw: endpoint {
remote-endpoint = <&tcphy0_typec_orien_sw>;
};
};

port@1 {
reg = <1>;

usbc_role_sw: endpoint {
remote-endpoint = <&dwc3_0_role_switch>;
};
};

port@2 {
reg = <2>;

usbc_dp: endpoint {
remote-endpoint = <&tcphy0_typec_dp>;
};
};
};
};

&usbdrd_dwc3_0 {
status = "okay";
usb-role-switch;

port {
#address-cells = <1>;
#size-cells = <0>;
dwc3_0_role_switch: endpoint@0 {
reg = <0>;
remote-endpoint = <&usbc_role_sw>;
};
};
};

&tcphy0_usb3 {
orientation-switch;

port {
tcphy0_typec_orien_sw: endpoint {
remote-endpoint = <&usbc_orien_sw>;
};
};
};

&tcphy0_dp {
mode-switch;

port {
#address-cells = <1>;
#size-cells = <0>;

tcphy0_typec_dp: endpoint@0 {
reg = <0>;
remote-endpoint = <&usbc_dp>;
};
};
};

Peter

Peter

[0]: https://lore.kernel.org/all/20250715112456.101-6-kernel@xxxxxxxxxx/

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

--
Best,
Chaoyi