Re: [PATCH 1/5] dt-bindings: connector: add optional properties for Type-B

[Hans de Goede]

Hi,

On 11-03-19 06:33, Chunfeng Yun wrote:
> Hi,
>
> On Fri, 2019-03-08 at 13:07 +0100, Hans de Goede wrote:
> > Hi,
> >
> > On 08-03-19 07:13, Chunfeng Yun wrote:
> > > Add id-gpios, vbus-gpios, vbus-supply and pinctrl properties for
> > > usb-b-connector
> > >
> > > Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
> > > ---
> > >    .../devicetree/bindings/connector/usb-connector.txt    | 10 ++++++++++
> > >    1 file changed, 10 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/connector/usb-connector.txt b/Documentation/devicetree/bindings/connector/usb-connector.txt
> > > index a9a2f2fc44f2..7a07b0f4f973 100644
> > > --- a/Documentation/devicetree/bindings/connector/usb-connector.txt
> > > +++ b/Documentation/devicetree/bindings/connector/usb-connector.txt
> > > @@ -17,6 +17,16 @@ Optional properties:
> > >    - self-powered: Set this property if the usb device that has its own power
> > >      source.
> > >    
> > > +Optional properties for usb-b-connector:
> > > +- id-gpios: gpio for USB ID pin.
> >
> > What about boards where the ID pin is *not* connected to a GPIO,
> > but e.g. to a special pin on the PMIC which can also detect
> > an ACA adapter ? Currently this case is handled by extcon
> > drivers, but we have no way to set e.g. vbus-supply for the
> > connector. Maybe in this case the usb-connector node should
> > be a child of the PMIC node ?
> Yes, it would be, PMIC is in charger of detecting the status of ID pin

Ok, then I think this should be documented too.

> > And in many cases there also is a mux to switch the datalines
> > between the host and device(gadget) controllers, how should
> > that be described in this model?  See the new usb-role-switch
> > code under drivers/usb/roles
> >
> > In some cases the mux is controlled through a gpio, so we
> > may want to add a "mux-gpios" here in which case we also
> > need to define what 0/1 means.
> I'm not sure, the mux seems not belong to this connector,
> and may need another driver to register usb-role-switch,
> similar to:
>
> [v2,2/2] usb: typec: add typec switch via GPIO control
> https://patchwork.kernel.org/patch/10834327/

Right the mux/role-switch will need a driver, but the "owner"
of the usb_connector, e.g. the PMIC or the owner of the
id GPIO pin needs to know which device is the role-switch so
that it can set the role correctly based on the id-pin.

Your binding already contains Vbus info, allowing the owner
of the usb_connector to enable/disable Vbus based on the id-pin,
but the owner will also be responsible for setting the role-switch.

Note we cannot simply assume there will be only one role-switch,
we really need some link from the usb_connector to the role-switch
(or if it is a GPIO driven role-switch simply a role-switch-gpios
member in the usb_connector).

Regards,

Hans