linux-kernel - Re: [PATCH 2/2] Documentation: DT: bindings: input: Add documentation for cyttsp5

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Date:   Wed, 7 Jun 2017 13:40:32 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Mylène Josserand 
        <mylene.josserand@...e-electrons.com>, fery@...ress.com,
        mark.rutland@....com, linux-kernel@...r.kernel.org,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        thomas.petazzoni@...e-electrons.com,
        maxime.ripard@...e-electrons.com
Subject: Re: [PATCH 2/2] Documentation: DT: bindings: input: Add
 documentation for cyttsp5

On Wed, Jun 07, 2017 at 03:26:03PM -0500, Rob Herring wrote:
> On Mon, May 29, 2017 at 04:45:38PM +0200, Mylène Josserand wrote:
> > Add the Cypress TrueTouch Generation 5 touchscreen device tree bindings
> > documentation. It can use I2C or SPI bus.
> > This touchscreen can handle some defined zone that are designed and
> > sent as button. To be able to customize the keycode sent, the
> > "linux,code" property in a "button" sub-node can be used.
> 
> "documentation" twice in the subject makes for a long subject. 
> The preferred subject prefix is "dt-bindings: input: ..."
> 
> > 
> > Signed-off-by: Mylène Josserand <mylene.josserand@...e-electrons.com>
> > ---
> >  .../bindings/input/touchscreen/cyttsp5.txt         | 55 ++++++++++++++++++++++
> 
> cypress,cyttsp5.txt matching the compatible is preferred.
> 
> >  1 file changed, 55 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/cyttsp5.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/input/touchscreen/cyttsp5.txt b/Documentation/devicetree/bindings/input/touchscreen/cyttsp5.txt
> > new file mode 100644
> > index 000000000000..713a377b5039
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/input/touchscreen/cyttsp5.txt
> > @@ -0,0 +1,55 @@
> > +* Cypress cyttsp touchscreen controller, generation 5
> > +
> > +Required properties:
> > + - compatible		: must be "cypress,cyttsp5"
> > + - reg			: Device I2C address or SPI chip select number
> > + - interrupt-parent	: the phandle for the gpio controller
> > +			  (see interrupt binding[0]).
> > + - interrupts		: (gpio) interrupt to which the chip is connected
> > +			  (see interrupt binding[0]).
> > +
> > +Optional properties (many of them coming from touchscreen binding[1]):
> > + - reset-gpios		: the reset gpio the chip is connected to
> > +			  (see GPIO binding[2] for more details).
> > + - touchscreen-size-x	: horizontal resolution of touchscreen (in pixels)
> 
> Just "see ./touchscreen.txt" is enough description.
> 
> > + - touchscreen-size-y	: vertical resolution of touchscreen (in pixels)
> > + - touchscreen-fuzz-x	: horizontal noise value of the absolute input device
> > +			  (in pixels)
> > + - touchscreen-fuzz-y	: vertical noise value of the absolute input device
> > +			  (in pixels)
> > +
> > +This touchscreen can handle some buttons that are touchscreen's defined zones.
> > +Each button's event can be customized using a sub-node properties:
> > +	- linux,code: Keycode to emit.
> > +
> > +[0]: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
> > +[1]: Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt
> > +[2]: Documentation/devicetree/bindings/gpio/gpio.txt
> > +
> > +Example:
> > +&i2c0 {
> > +	[...]
> > +
> > +	tsc@24 {
> 
> touchscreen@24
> 
> > +		compatible = "cypress,cyttsp5";
> > +		reg = <0x24>;
> > +
> > +		pinctrl-names = "default";
> > +		pinctrl-0 = <&tp_reset_ds203>;
> > +		interrupt-parent = <&pio>;
> > +		interrupts = <1 5 IRQ_TYPE_LEVEL_LOW>;
> > +		reset-gpios = <&pio 7 1 GPIO_ACTIVE_HIGH>;
> > +
> > +		button@0 {
> 
> unit addresses need a reg property. If 0,1,2 are meaningful numbers for 
> the hardware, then it makes sense to add here.

Another option would be just say:

		linux,keycodes = <KEY_HOMEPAGE>, <KEY_MENU>, <KEY_BACK>;

I am wondering though: you read number of button supported by the device
from HID_SYSINFO_BTN_OFFSET, can you also get button assignment form
the device as well?

And the biggest question of all: since you refer to HID descriptors in
your driver, is it a HID device and should it be driven by HID susbystem
instead of relying on a custom driver?

> 
> > +			linux,code = <KEY_HOMEPAGE>;
> > +		};
> > +
> > +		button@1 {
> > +			linux,code = <KEY_MENU>;
> > +		};
> > +
> > +		button@2 {
> > +			linux,code = <KEY_BACK>;
> > +		};
> > +	};
> > +};
> > -- 
> > 2.11.0
> > 

Thanks.

-- 
Dmitry