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

schowdhu
2021-10-07T09:25:29Z

On 2021-10-05 22:07, Bjorn Andersson wrote:
> On Tue 05 Oct 06:11 PDT 2021, schowdhu@codeaurora.org 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@codeaurora.org>
>> > > ---
>> > > .../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@codeaurora.org/
>>
>
> 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
>> > >
>> > >