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

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Message-ID: <1552360688.10179.55.camel@mhfsdcap03>
Date:   Tue, 12 Mar 2019 11:18:08 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     Hans de Goede <hdegoede@...hat.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
        Li Jun <jun.li@....com>,
        "Badhri Jagan Sridharan" <badhri@...gle.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Min Guo <min.guo@...iatek.com>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH 1/5] dt-bindings: connector: add optional properties for
 Type-B

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@...iatek.com>
> >>> ---
> >>>    .../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? 

Thanks
> 
> 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
>