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SubjectRe: [PATCH 1/2] dt-bindings: chrome: Add cros-ec-typec mux props
Hi Rob,

Thanks for reviewing the patch! Kindly see inline:

On Fri, May 29, 2020 at 2:55 PM Rob Herring <robh@kernel.org> wrote:
>
> > > " 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."
> > > >
> > > > > + 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.
> > > >
> > > > 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

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