linux-kernel - Re: [PATCH] dt-binding: usb: add usb-role-switch property

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Message-ID: <20190502194905.GA22144@bogus>
Date:   Thu, 2 May 2019 14:49:05 -0500
From:   Rob Herring <robh@...nel.org>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Biju Das <biju.das@...renesas.com>,
        Yu Chen <chenyu56@...wei.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Min Guo <min.guo@...iatek.com>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>
Subject: Re: [PATCH] dt-binding: usb: add usb-role-switch property

On Sun, Apr 28, 2019 at 08:27:46PM +0800, Chunfeng Yun wrote:
> Add a property usb-role-switch to tell Dual-Role controller driver
> that use USB Role Switch framework to handle the role switch between
> host mode and device mode, it's useful when the driver has already
> supported other ways, such as extcon framework etc.
> 
> Cc: Biju Das <biju.das@...renesas.com>
> Cc: Yu Chen <chenyu56@...wei.com>
> Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>
> ---
> v1:
> the property is discussed in:
> [v2,2/7] dt-bindings: usb: renesas_usb3: add usb-role-switch property
> https://patchwork.kernel.org/patch/10852497/
> 
> Mediatek and Hisilicon also try to use it:
> [v4,3/6] dt-bindings: usb: mtu3: add properties about USB Role Switch
> https://patchwork.kernel.org/patch/10918385/
> [v4,6/6] usb: mtu3: register a USB Role Switch for dual role mode
> https://patchwork.kernel.org/patch/10918367/
> 
> [v6,10/13] usb: dwc3: Registering a role switch in the DRD code
> https://patchwork.kernel.org/patch/10909981/
> ---
>  Documentation/devicetree/bindings/usb/generic.txt | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/usb/generic.txt b/Documentation/devicetree/bindings/usb/generic.txt
> index 0a74ab8dfdc2..c73950b72513 100644
> --- a/Documentation/devicetree/bindings/usb/generic.txt
> +++ b/Documentation/devicetree/bindings/usb/generic.txt
> @@ -30,6 +30,9 @@ Optional properties:
>  			optional for OTG device.
>   - adp-disable: tells OTG controllers we want to disable OTG ADP, ADP is
>  			optional for OTG device.
> + - usb-role-switch: tells Dual-Role USB controller driver that we want to use
> +			USB Role Switch framework to handle the role switch
> +			between host mode and device mode.

Please describe this in terms of h/w functionality, not drivers and 
Linux things.

Rob