Re: [PATCH 2/7] dt-bindings: usb: dwc3: Add a gpio-usb-connector example

[Bryan O'Donoghue]

On 19/03/2020 16:40, Stephen Boyd wrote:
> Quoting Bryan O'Donoghue (2020-03-19 08:22:14)
> > On 19/03/2020 01:08, Stephen Boyd wrote:
> > > Maybe it should be a virtual node at the root of the DT if it's GPIO
> > > controlled? And then the phy can be connected to the usb connector
> > > through the graph binding.
> >
> > Graph binding can probably work.
> >
> > Re: the PHY.
> >
> > For myself the hardware model is
> >
> > Connector -> PHY -> Host controller -> Host controller wrapper
> >
> > Only
> >
> > Connector -> Host controller -> Host controller wrapper
> >
> > care about the USB role though.
> >
> > If your PHY did care about the role, you'd really need to write a
> > connector/phy type-c type driver, to detect the state and toggle your
> > PHY bits before doing usb_role_switch_set_role() back to DWC3.
>
> Yes some PHYs do care about the role. Sometimes they have to toggle some
> bit to switch between host and gadget mode for example. I haven't fully
> read this patch series but maybe the PHY can be the one that controls
> the gpio for the connector?

Previous version of the PHY from 2019 had extcon toggling vbus.

Since extcon is going away, we moved go usb-gpio

https://lwn.net/ml/devicetree/20190905175802.GA19599@xxxxxxxxxxxxxxxxxxxxxxxx/

https://lwn.net/ml/devicetree/5d71edf5.1c69fb81.1f307.fdd6@xxxxxxxxxxxxx/

usb-gpio-conn handle VBUS and notifies via the USB role switch API.

Which if the connector is a child of the controller "just works" but, 
maybe with a little bit of work DT <port> references could do the same 
thing and the connector wouldn't need to be declared as a child.

> We (ChromeOS) need to integrate the type-c connector class, etc. on
> sc7180 with the dwc3 driver and the current thinking has the type-c
> connectors underneath the cros_ec node because the EC is the type-c
> manager. The EC will have a type-c driver associated with it.

right and you don't want, doesn't work or doesn't make sense, to declare 
cros_ec as a child of DWC3, fair enough.

I guess a DT remote-endpoint{} will do the job.

Something like:
arch/arm64/boot/dts/freescale/imx8mn-evk.dtsi

---
bod