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

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Message-ID: <158464980279.152100.13680630167113607572@swboyd.mtv.corp.google.com>
Date:   Thu, 19 Mar 2020 13:30:02 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Bryan O'Donoghue <bryan.odonoghue@...aro.org>, balbi@...nel.org,
        gregkh@...uxfoundation.org, linux-usb@...r.kernel.org
Cc:     linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        bjorn.andersson@...aro.org, jackp@...eaurora.org, robh@...nel.org,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org
Subject: Re: [PATCH 2/7] dt-bindings: usb: dwc3: Add a gpio-usb-connector example

Quoting Bryan O'Donoghue (2020-03-19 11:03:58)
> On 19/03/2020 16:40, Stephen Boyd wrote:
> > 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@jackp-linux.qualcomm.com/
> 
> https://lwn.net/ml/devicetree/5d71edf5.1c69fb81.1f307.fdd6@mx.google.com/
> 
> 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
> 

Yes something like that, but it looks like that dtsi file has the usb
host controller connected through a remote-endpoint to the type-c
connector. I was under the impression that it would only be the phy that
is connected this way because it's possible for there to be multiple
different phys that drive data out through one connector. For example,
in type-c the DP phy can be different from the USB2 phy or USB3 phy and
there could even be other things like an HDMI phy too that all go to the
same connector.