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

[Hans de Goede]

Hi,

On 3/13/19 11:15 AM, Chunfeng Yun wrote:
> Hi,
> On Tue, 2019-03-12 at 13:45 +0100, Hans de Goede wrote:
> > Hi,
> > On 12-03-19 04:18, Chunfeng Yun wrote:
> > > Hi,
> > > On Mon, 2019-03-11 at 09:06 +0100, Hans de Goede wrote:
> > > > 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.
> > > In this patch series, I make usb_connector driver enable/disable Vbus,
> > > but not the parent(USB controller) of usb_connector which registers a
> > > usb-role-switch, which way do you think it is better?
> >
> > IMHO there should not be a driver for the usb_connector child-node,
> > only for the parent-device of that child-node.
> If so, each USB controller driver should process this special case by
> itself when use a gpio to detect the status of ID pin, it's not a
> friendly way. And it's easy by using extcon-usb-gpio driver before, so
> we also want to provide a simple way when support usb_connector, no
> matter what method we choose.
>
> Ideally, the only one thing that USB controller driver need to do, just
> register a usb-role-switch, and leave decision when switch the role to
> other drivers, such as type-C, PMIC/charger, also include gpio
>
> > There are going to be too many specific setups surrounding PMICs to
> > be able to do a single generic driver for the connector.
> Fortunately, these patches only focus on the simplest gpio driven role
> switch :)

In that case there should be an extra compatible added to the
usb_b_connector node to which the "simple gpio" driver binds,
so that not all devicetree-s declaring a usb_b_connector child-node
automatically get that driver bound, and the gpio / vbus
properties should be mandatory properties for usb_b_connector
child nodes declaring the extra compatible, rather then being
optional for the generic compatible.

Regards,

Hans