linux-kernel - Re: [PATCH v3 1/4] dt-bindings: Add cros-ec Type C port driver

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Date:   Wed, 4 Mar 2020 09:53:40 -0800
From:   Prashant Malani <pmalani@...omium.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        linux-kernel@...r.kernel.org, enric.balletbo@...labora.com,
        bleung@...omium.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Guenter Roeck <groeck@...omium.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v3 1/4] dt-bindings: Add cros-ec Type C port driver

Hi Rob,

Thanks for reviewing the patch. Please see inline.

On Thu, Feb 27, 2020 at 05:15:47PM -0600, Rob Herring wrote:
> On Thu, Feb 27, 2020 at 05:12:16PM +0200, Heikki Krogerus wrote:
> > Hi,
> > 
> > On Wed, Feb 19, 2020 at 04:30:55PM -0800, Prashant Malani wrote:
> > > Some Chrome OS devices with Embedded Controllers (EC) can read and
> > > modify Type C port state.
> > > 
> > > Add an entry in the DT Bindings documentation that lists out the logical
> > > device and describes the relevant port information, to be used by the
> > > corresponding driver.
> > > 
> > > Signed-off-by: Prashant Malani <pmalani@...omium.org>
> > > ---
> > > 
> > > Changes in v3:
> > > - Fixed license identifier.
> > > - Renamed "port" to "connector".
> > > - Made "connector" be a "usb-c-connector" compatible property.
> > > - Updated port-number description to explain min and max values,
> > >   and removed $ref which was causing dt_binding_check errors.
> > > - Fixed power-role, data-role and try-power-role details to make
> > >   dt_binding_check pass.
> > > - Fixed example to include parent EC SPI DT Node.
> > > 
> > > Changes in v2:
> > > - No changes. Patch first introduced in v2 of series.
> > > 
> > >  .../bindings/chrome/google,cros-ec-typec.yaml | 86 +++++++++++++++++++
> > >  1 file changed, 86 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml b/Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml
> > > new file mode 100644
> > > index 00000000000000..97fd982612f120
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml
> > > @@ -0,0 +1,86 @@
> > > +# SPDX-License-Identifier: GPL-2.0-only
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/chrome/google,cros-ec-typec.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Google Chrome OS EC(Embedded Controller) Type C port driver.
> > > +
> > > +maintainers:
> > > +  - Benson Leung <bleung@...omium.org>
> > > +  - Prashant Malani <pmalani@...omium.org>
> > > +
> > > +description:
> > > +  Chrome OS devices have an Embedded Controller(EC) which has access to
> > > +  Type C port state. This node is intended to allow the host to read and
> > > +  control the Type C ports. The node for this device should be under a
> > > +  cros-ec node like google,cros-ec-spi.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: google,cros-ec-typec
> > > +
> > > +  connector:
> > > +    description: A node that represents a physical Type C connector port
> > > +      on the device.
> > > +    type: object
> > > +    properties:
> > > +      compatible:
> > > +        const: usb-c-connector
> > > +      port-number:
> > > +        description: The number used by the Chrome OS EC to identify
> > > +          this type C port. Valid values are 0 - (EC_USB_PD_MAX_PORTS - 1).
> > > +      power-role:
> > > +        description: Determines the power role that the Type C port will
> > > +          adopt.
> > > +        maxItems: 1
> > > +        contains:
> > > +          enum:
> > > +            - sink
> > > +            - source
> > > +            - dual
> > > +      data-role:
> > > +        description: Determines the data role that the Type C port will
> > > +          adopt.
> > > +        maxItems: 1
> > > +        contains:
> > > +          enum:
> > > +            - host
> > > +            - device
> > > +            - dual
> > > +      try-power-role:
> > > +        description: Determines the preferred power role of the Type C port.
> > > +        maxItems: 1
> > > +        contains:
> > > +          enum:
> > > +            - sink
> > > +            - source
> > > +            - dual
> > > +
> > > +    required:
> > > +      - port-number
> > > +      - power-role
> > > +      - data-role
> > > +      - try-power-role
> > 
> > Do you really need to redefine those?
> 
> No.
> 
> > 
> > I think you just need to mention that there is a required sub-node
> > "connector", and the place where it's described. So something
> > like this:
> > 
> >         Required sub-node:
> >         - connector : The "usb-c-connector". The bindings of the
> >           connector node are specified in:
> > 
> >                 Documentation/devicetree/bindings/connector/usb-connector.txt
> 
> Ideally, we'd convert this to schema first and then here just have:

I've converted this to schema here: https://lkml.org/lkml/2020/3/4/790
I've sent that patch separately from this series, since there is ongoing
discussion regarding the structure of the bindings (and use of OF graph
API) here.


> 
> connector:
>   $ref: /schemas/connector/usb-connector.yaml#
> 
> > 
> > 
> > Then you just need to define the Chrome OS EC specific properties, so
> > I guess just the "port-number".
> 
> 'reg' as Stephen suggested.
> 
> Rob