linux-kernel - Re: [PATCH v4 1/6] dt-bindings: usb: musb: Add support for MediaTek musb controller

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Date:   Fri, 25 Jan 2019 10:07:26 +0800
From:   Min Guo <min.guo@...iatek.com>
To:     Bin Liu <b-liu@...com>, Rob Herring <robh@...nel.org>
CC:     Mark Rutland <mark.rutland@....com>, <devicetree@...r.kernel.org>,
        <hdegoede@...hat.com>, <tony@...mide.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Alan Stern <stern@...land.harvard.edu>,
        <chunfeng.yun@...iatek.com>, <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4 1/6] dt-bindings: usb: musb: Add support for MediaTek
 musb controller

Hi Bin,

Thanks for your help.

Hi Rob,

I find that Samsung describes the usb-connector attribute in DTS, and
uses a private driver.
And try to write DTS as following:

usb-connector node:
musb_con: musb_connector{
    compatible = "linux,extcon-usb-gpio","usb-b-connector";
    lable = "micro-USB";
    type = "micro";
    id-gpio = <&pio 44 GPIO_ACTIVE_HIGH>
    vbus-supply = <&usb_vbus>;
    port {
        usb_to_connector: endpoint {
            remote-endpoint = <&connector_to_usb>;
        };
    };
};

usb node:
&usb2{
    status = "okay";
    port {
        connector_to_usb: endpoint {
            remote-endpoint = <&usb_to_connector>;
        };
    };
}

Can I describe usb-connector like this? Or can you give me some advices?

Regards,
Min.

On Tue, 2019-01-22 at 08:33 -0600, Bin Liu wrote:
> Hi Min,
> 
> On Tue, Jan 22, 2019 at 05:36:13PM +0800, Min Guo wrote:
> > Hi Bin,
> > 
> > Sorry to bother you again, I encounter a problem about the extcon
> > property.
> > 
> > I don't find a common driver describing the usb-connector. Is
> > there any driver that I can refer to, specially the way to switch MUSB
> > controller between host and device mode? 
> > If it needs to implement by myself, is it possible to emulate an
> > usb-connector driver by extcon-usb-gpio, and also use the notifier
> > mechanism or can you give me some advices?
> 
> I am afraid I am unable to help you on this. I wasn't really pay
> attention when usb-connector was introduced and not sure how it can
> replace extcon. Now after read usb-connector.txt, it seems the binding
> only defines a/b/c-connector, but not ab-connector, and there is no
> enough information (at least for me) explaining how VBUS and ID fix into
> this usb-connector binding.
> 
> Maybe Rob can provide some hint.
> 
> Regards,
> -Bin.