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Date: Thu, 1 Dec 2016 15:34:34 +0100
From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
To: Brian Norris <briannorris@chromium.org>
Cc: Jiri Kosina <jikos@kernel.org>, Caesar Wang <wxt@rock-chips.com>,
        linux-rockchip@lists.infradead.org, Rob Herring <robh+dt@kernel.org>,
        linux-input@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Doug Anderson <dianders@chromium.org>
Subject: Re: [PATCH v2 1/2] devicetree: i2c-hid: Add Wacom digitizer +
 regulator support
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On Nov 30 2016 or thereabouts, Brian Norris wrote:
> From: Caesar Wang <wxt@rock-chips.com>
> 
> Add a compatible string and regulator property for Wacom W9103
> digitizer. Its VDD supply may need to be enabled before using it.
> 
> Signed-off-by: Caesar Wang <wxt@rock-chips.com>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Jiri Kosina <jikos@kernel.org>
> Cc: linux-input@vger.kernel.org
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> v1 was a few months back. I finally got around to rewriting it based on
> DT binding feedback.
> 
> v2:
>  * add compatible property for wacom
>  * name the regulator property specifically (VDD)
> 
>  Documentation/devicetree/bindings/input/hid-over-i2c.txt | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/input/hid-over-i2c.txt b/Documentation/devicetree/bindings/input/hid-over-i2c.txt
> index 488edcb264c4..eb98054e60c9 100644
> --- a/Documentation/devicetree/bindings/input/hid-over-i2c.txt
> +++ b/Documentation/devicetree/bindings/input/hid-over-i2c.txt
> @@ -11,12 +11,16 @@ If this binding is used, the kernel module i2c-hid will handle the communication
>  with the device and the generic hid core layer will handle the protocol.
>  
>  Required properties:
> -- compatible: must be "hid-over-i2c"
> +- compatible: must be "hid-over-i2c", or a device-specific string like:
> +    * "wacom,w9013"

NACK on this one.

After re-reading the v1 submission I realized Rob asked for this change,
but I strongly disagree.

HID over I2C is a generic protocol, in the same way HID over USB is. We
can not start adding device specifics here, this is opening the can of
worms. If the device is a HID one, nothing else should matter. The rest
(description of the device, name, etc...) is all provided by the
protocol.

>  - reg: i2c slave address
>  - hid-descr-addr: HID descriptor address
>  - interrupt-parent: the phandle for the interrupt controller
>  - interrupts: interrupt line
>  
> +Optional properties:
> +- vdd-supply: phandle of the regulator that provides the supply voltage.

Agree on this one however.

Cheers,
Benjamin

> +
>  Example:
>  
>  	i2c-hid-dev@2c {
> -- 
> 2.8.0.rc3.226.g39d4020
>