Re: [PATCH V0 1/7] dt-bindings: connector: Add property for eud type c connector

[schowdhu]

On 2021-10-05 22:07, Bjorn Andersson wrote:
> On Tue 05 Oct 06:11 PDT 2021, schowdhu@xxxxxxxxxxxxxx wrote:
>
> > On 2021-10-04 22:07, Rob Herring wrote:
> > > On Mon, Oct 04, 2021 at 04:46:19PM +0530, Souradeep Chowdhury wrote:
> > > > Added the property for EUD(Embedded USB Debug) connector.Added
> > > > the "reg" and "interrupts" property which is needed for EUD.
> > >
> > > You are going to need a better explanation of this h/w.
> >
> > Ack. Will update this with the detailed hardware description
> > in the next version.
> >
> > >
> > > >
> > > > Signed-off-by: Souradeep Chowdhury <schowdhu@xxxxxxxxxxxxxx>
> > > > ---
> > > >  .../devicetree/bindings/connector/usb-connector.yaml      | 15
> > > > +++++++++++++++
> > > >  1 file changed, 15 insertions(+)
> > > >
> > > > diff --git
> > > > a/Documentation/devicetree/bindings/connector/usb-connector.yaml
> > > > b/Documentation/devicetree/bindings/connector/usb-connector.yaml
> > > > index 7eb8659..908129f 100644
> > > > --- a/Documentation/devicetree/bindings/connector/usb-connector.yaml
> > > > +++ b/Documentation/devicetree/bindings/connector/usb-connector.yaml
> > > > @@ -30,6 +30,21 @@ properties:
> > > >            - const: samsung,usb-connector-11pin
> > > >            - const: usb-b-connector
> > > >
> > > > +      - items:
> > > > +          - enum:
> > > > +              - qcom,sc7280-usb-connector-eud
> > > > +          - const: qcom,usb-connector-eud
> > > > +          - const: usb-c-connector
> > > > +
> > > > +  reg:
> > > > +    items:
> > > > +      - description: EUD Base Register Region
> > > > +      - description: EUD Mode Manager Region
> > >
> > > A connector node represents the physical connector on a board. That
> > > can't really be an MMIO peripheral. Maybe you need a node for EUD and
> > > then it should have a connector child node? Don't really know without
> > > understanding this h/w.
> >
> > As per the previous discussion on the EUD, it was agreed upon to map 
> > EUD
> > as a type C connector and use Role-Switch to change the USB role 
> > instead
> > of extcon interface that was being used previously. The link for the 
> > same
> > is as follows:-
> >
> > https://lore.kernel.org/lkml/5db1a666-62ec-c850-6626-ad33d337b452@xxxxxxxxxxxxxx/
>
> Not using extcon is the right thing, but perhaps we should make the EUD
> a role_switch provider and client, so that we can describe how it sits
> inbetween the connector and the controller.
>
> That way it has the power to pass through or override requests from the
> upstream role-switcher, based on the status of EUD.
>
>
> That said, I'm still curious to what happens if I renegotiate the roles
> dynamically in a Type-C environment, while enabling EUD. How would the
> device on the other end of the cable know that it's supposed to be a
> host? Or there's simply a reset of the link when this happens?
>
> Thanks,
> Bjorn

Hi Bjorn,

By making EUD Role-Switch provider and client do you mean that
we should have a EUD node which will have a connector node as
child and this connector node will have a port that points towards
the drd role-switch?

So that my device tree node will look like the following in that case

eud@88e0000 {
        compatible = "qcom,usb-connector-eud";
        reg = <0 0x88e0000 0 0x2000>,
              <0 0x88e2000 0 0x1000>;
        interrupt-parent = <&pdc>;
        interrupts = <11 IRQ_TYPE_LEVEL_HIGH>;
        usb_con: connector {
                compatible = "usb-c-connector";
                label = "USB-C";
                port {
                      eud_usb_output: endpoint {
                      remote-endpoint = <&eud_usb3_input>;
                 };
        };

};


@usb2 {
    dwc3 {
       usb-role-switch;
       port {
             eud_usb3_input: endpoint {
                   remote-endpoint = <&eud_usb_output>;
             };
     };
};

Also EUD functions only in device mode, so when the role-switch is done 
by the controller
to set the device mode, the PC on the other end becomes the host.

Thanks,
Souradeep

> > >
> > > > +
> > > > +  interrupts:
> > > > +    description:
> > > > +      EUD interrupt
> > > > +
> > > >    label:
> > > >      description: Symbolic name for the connector.
> > > >
> > > > --
> > > > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
> > > > member
> > > > of Code Aurora Forum, hosted by The Linux Foundation
> > > >
> > > >