Re: [PATCH v3 2/3] Input: cyttsp - add device tree bindings

[Dmitry Torokhov]

On Mon, Jan 11, 2016 at 06:54:23PM +0100, Oreste Salerno wrote:
> 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@xxxxxxxxxx>
> > > ---
> > >  .../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().

It doe snot have to and it will not if you use
touchscreen_parse_properties(). But you are right, fuzz is reserved for
software de-jittering, and it can be changed at any time from userspace
at input device level, but will not be communicated to the hardware. I
think hardware-based filtering is hardware-specific and I think
having a separate property is fine for it. We can still standardize on
name, units, etc though.

>  
> > > +- 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?  

Please address the items from my other email and I should be able to
pick it up.

Thanks.

-- 
Dmitry