Hi Rob,

Thanks for reviewing the patch! Kindly see inline:

On Fri, May 29, 2020 at 2:55 PM Rob Herring [off-list ref] wrote:

quoted

quoted

" Reference to a DT node for the USB Type C Multiplexer controlling the
data lines routing for this connector. This switch is assumed registered
with the Type C connector class framework, which requires it to be named
this way."

quoted

quoted

+          mode-switch:
+            description: Reference to a DT node for the USB Type C Multiplexer
+              controlling the data lines routing for this connector.

This is for alternate mode muxing I presume.

Yes, that's right.

quoted

We already have a mux-control binding. Why not use that here?

Heikki might be able to offer more insight into why this is the case,
since the connector class framework seems to expect a phandle and for
the device driver to implement a "set" command. Heikki, would you happen to know?

The mode-switch here would actually represent the "consumer" part in
the mux-control bindings. So the mux-controls would describe the
relationship between the "mode-switch" and the mux controller(s),
while the mode-switch property describes the relationship between
something like USB Type-C Port Manager (or this cros_ec function) and
the "mux consumer".

The "USB Type-C Port Manager" is not just the parent node in your case?

Can you point me to what you expect your DT to look like showing the
mode switch node, the connector, the USB host(s), and the DP/HDMI
bridge/output?

Caveat: I'm not a DT expert and not well-versed with the mux-control
bindings, so Heikki may be able to describe these better.
That said, here is my attempt to show the nodes you requested, cobbled
together from the Rockchip rk3399 DTSI[1] and
swboyd's connector binding example [2].

Nodes truncated and unrelated fields omitted in the interest of brevity:

// Chrome OS EC Type C Port Manager.
typec {
    compatible = "google,cros-ec-typec";
    #address-cells = <1>;
    #size-cells = <0>;

    connector@0 {
        compatible = "usb-c-connector";
        reg = <0>;
        power-role = "dual";
        data-role = "dual";
        try-power-role = "source";
        mode-switch = <&foo_mux>;
        // Other switches can point to the same mux.
        ....
    };
};

// Mux switch
// TODO: Can possibly embed this in the PHY controller node itself?
foo_mux {
    compatible = "vendor,typec-mux";
    mux-gpios = <&gpio_controller 23 GPIO_ACTIVE_HIGH>;

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

        port@1 {
            reg = <1>;
            mux_usb_in: endpoint1 {
                remote-endpoint = <&usb3_phy_out>;
            };
        };
    };
};

// Type C PHY Controller.
tcphy0: phy@ff7c0000 {
    compatible = "rockchip,rk3399-typec-phy";
    reg = <0x0 0xff7c0000 0x0 0x40000>;
    ...
    tcphy0_dp: phy@dc00000 {
        compatible = "soc,dp-phy";
        reg = <0xdc00000 0x1000>;
        ports {
            port@0 {
                reg = <0>;
                dp_phy_out: endpoint {
                    remote-endpoint = <&mux_dp_in>;
                };
            };
        };
    };

    tcphy0_usb3: phy@db00000 {
        compatible = "soc,usb3-phy";
        reg = <0xdb00000 0x1000>;
        ports {
            port@0 {
                reg = <0>;
                usb3_phy_out: endpoint {
                    remote-endpoint = <&mux_usb3_in>;
                };
            };
        };
    };
};


// USB3 Host controller
usbdrd3_0: usb@fe800000 {
    compatible = "rockchip,rk3399-dwc3";
    #address-cells = <2>;
    #size-cells = <2>;
    clocks = ...;
    clock-names = ...;
    status = "disabled";

    usbdrd_dwc3_0: usb@fe800000 {
        compatible = "snps,dwc3";
        reg = <0x0 0xfe800000 0x0 0x100000>;
        interrupts = <GIC_SPI 105 IRQ_TYPE_LEVEL_HIGH 0>;
        clocks = ...;
        clock-names = ...;
        dr_mode = "otg";
        phys = <&tcphy0_usb3>;
        phy-names = "usb3-phy";
        phy_type = "utmi_wide";
        power-domains = <&power RK3399_PD_USB3>;
        status = "disabled";
    };
};

// DP controller
cdn_dp: dp@fec00000 {
    compatible = "rockchip,rk3399-cdn-dp";
    reg = <0x0 0xfec00000 0x0 0x100000>;
    interrupts = ...;
    clocks = ...;
    clock-names = ...;
    phys = <&tcphy0_dp>;
    ...
    ports {
        dp_in: port {
            #address-cells = <1>;
            #size-cells = <0>;

            dp_in_vopb: endpoint@0 {
                reg = <0>;
                remote-endpoint = <&vopb_out_dp>;
            };

            dp_in_vopl: endpoint@1 {
                reg = <1>;
                remote-endpoint = <&vopl_out_dp>;
            };
        };
    };
};

[1] : https://chromium.googlesource.com/chromiumos/third_party/kernel/+/refs/heads/chromeos-5.4/arch/arm64/boot/dts/rockchip/rk3399.dtsi
[2]: https://lkml.org/lkml/2020/2/28/1081

Hope this helps, and my apologies in advance for any errors.

Best regards,

-Prashant

Rob