Re: [RFC PATCH v2 1/4] dt-bindings: input: Add support for the MPR121 without interrupt line

[Rob Herring <robh@kernel.org>]

On Fri, May 17, 2019 at 03:12:50PM +0200, Michal Vokáč wrote:
> Normally, the MPR121 controller uses separate interrupt line to notify
> the I2C host that a key was touched/released. To support platforms that
> can not use the interrupt line, polling of the MPR121 registers can be
> used.

'separate' from what?

> 
> Signed-off-by: Michal Vokáč <michal.vokac@ysoft.com>
> ---
> Changes since v1:
> - Document the polled binding in the original file, do not create a new one.
>   (Rob)
> 
>  Documentation/devicetree/bindings/input/mpr121-touchkey.txt | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/input/mpr121-touchkey.txt b/Documentation/devicetree/bindings/input/mpr121-touchkey.txt
> index b7c61ee5841b..97f55273d473 100644
> --- a/Documentation/devicetree/bindings/input/mpr121-touchkey.txt
> +++ b/Documentation/devicetree/bindings/input/mpr121-touchkey.txt
> @@ -1,9 +1,14 @@
> -* Freescale MPR121 Controllor
> +* Freescale MPR121 Controller
>  
>  Required Properties:
> -- compatible:		Should be "fsl,mpr121-touchkey"
> +- compatible:		Should be one of:
> +			- "fsl,mpr121-touchkey" - MPR121 with interrupt line
> +			- "fsl,mpr121-touchkey-polled" - MPR121 with polling
>  - reg:			The I2C slave address of the device.
>  - interrupts:		The interrupt number to the cpu.
> +			In case of "fsl,mpr121-touchkey-polled" the interrupt
> +			line is not used and hence the interrupts property is
> +			not required.

Absence of the interrupts property is enough to determine polled mode 
and you don't need a separate compatible string.

>  - vdd-supply:		Phandle to the Vdd power supply.
>  - linux,keycodes:	Specifies an array of numeric keycode values to
>  			be used for reporting button presses. The array can
> -- 
> 2.1.4
>