linux-kernel - Re: [PATCH v3 2/3] Input: cyttsp

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Date:	Mon, 11 Jan 2016 18:54:23 +0100
From:	Oreste Salerno <oreste.salerno@...tom.com>
To:	Rob Herring <robh@...nel.org>
CC:	<linux-kernel@...r.kernel.org>, <linux-input@...r.kernel.org>,
	<fery@...ress.com>, <dmitry.torokhov@...il.com>,
	<pawel.moll@....com>, <mark.rutland@....com>,
	<ijc+devicetree@...lion.org.uk>, <galak@...eaurora.org>,
	<devicetree@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] Input: cyttsp - add device tree bindings

On Sun, Jan 10, 2016 at 09:01:56PM -0600, Rob Herring wrote:
> On Sun, Jan 10, 2016 at 06:36:08PM +0100, Oreste Salerno wrote:
> > Signed-off-by: Oreste Salerno <oreste.salerno@...tom.com>
> > ---
> >  .../bindings/input/touchscreen/cyttsp.txt          |  82 +++++++++++++
> >  drivers/input/touchscreen/cyttsp_core.c            | 134 +++++++++++++++++++--
> >  include/linux/input/cyttsp.h                       |   3 +
> >  3 files changed, 212 insertions(+), 7 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/cyttsp.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/input/touchscreen/cyttsp.txt b/Documentation/devicetree/bindings/input/touchscreen/cyttsp.txt
> > new file mode 100644
> > index 0000000..2dc5c65
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/input/touchscreen/cyttsp.txt
> > @@ -0,0 +1,82 @@
> > +* Cypress cyttsp touchscreen controller
> > +
> > +Required properties:
> > +- compatible		: must be "cypress,cyttsp-i2c" or "cypress,cyttsp-spi"
> > +- reg			: Device I2C address or SPI chip select number
> > +- spi-max-frequency 	: Maximum SPI clocking speed of the device (for cyttsp-spi)
> > +- 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]).
> > +- reset-gpios		: the reset gpio the chip is connected to
> > +			  (see GPIO binding[1] for more details).
> > +- touchscreen-size-x	: horizontal resolution of touchscreen (in pixels)
> > +- touchscreen-size-y	: vertical resolution of touchscreen (in pixels)
> > +- bootloader-key	: the 8-byte bootloader key that is required to switch
> > +			  the chip from bootloader mode (default mode) to
> > +			  application mode.
> > +			  This property has to be specified as an array of 8
> > +			  '/bits/ 8' values.
> > +
> > +Optional properties:
> > +- active-distance	: the distance in pixels beyond which a touch must move
> > +			  before movement is detected and reported by the device.
> > +			  Valid values: 0-15.
> 
> Wouldn't this be the same as touchscreen-fuzz-(x|y) which is the 
> replacement for the deprecated moving-threshold? 
>

It is somewhat related. But I understand that the touchscreen-fuzz-(x|y) properties
are meant to be used as parameters passed to input_set_abs_params(), which are used
for a SW-based jitter filtering.
The active-distance value instead is used to set a HW register in the chip which
effectively performs the filtering in the HW.
The driver is currently passing 0 as fuzz parameter to input_set_abs_params().
 
> > +- active-interval-ms	: the minimum period in ms between consecutive
> > +			  scanning/processing cycles when the chip is in active mode.
> > +			  Valid values: 0-255.
> > +- lowpower-interval-ms	: the minimum period in ms between consecutive
> > +			  scanning/processing cycles when the chip is in low-power mode.
> > +			  Valid values: 0-2550
> > +- touch-timeout-ms	: minimum time in ms spent in the active power state while no
> > +			  touches are detected before entering low-power mode.
> > +			  Valid values: 0-2550
> > +
> 
> Otherwise, looks fine.

I am still waiting for a review from the driver maintainer (Ferruh Yigit), but I see
that he hasn't been actively reviewing patches for the cyttsp* drivers for a while.
I wonder what would be the process in this case?