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Date: Tue, 7 Aug 2012 22:05:51 +0200
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Subject: Re: [PATCH 1/4] Input: cyttsp4 - bus driver for Cypress TMA4XX
 touchscreen devices
From: Javier Martinez Canillas <javier@dowhile0.org>
To: Ferruh Yigit <fery@cypress.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Kevin McNeely <kev@cypress.com>, Henrik Rydberg <rydberg@euromail.se>,
        Shawn Landden <shawnlandden@gmail.com>,
        Ashish Jangam <ashish.jangam@kpitcummins.com>,
        Olivier Sobrie <olivier@sobrie.be>, linux-input@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Tue, Aug 7, 2012 at 3:09 PM, Ferruh Yigit <fery@cypress.com> wrote:
> From: Ferruh YIGIT <fery@cypress.com>
>
> This driver is for Cypress TrueTouch(tm) Standard Product controllers,
> Generation4 devices.
>
> Driver consist of four main modules:
>
> Bus driver: Linux bus driver implementation, binds other modules.
> Core driver: Core module that communicate with TTSP controller.
> MT driver: MultiTouch driver, converts touch information to host specific
> touch events
> Adapter driver: Communication adapter between host and controller, like
> I2C or SPI.
>
> This is Cyttsp4 TTSP Bus Driver,
> Provides binding between Adapter, Core, and TTSP Modules.
>
> A complete set of corresponding Adapter, Core, and TTSP module
> devices and drivers must be registered with the TTSP Bus handler
>

Hi Ferruh,

There is already a driver in the kernel that supports Cypress
TrueTouch(TM) Standard Product (TTSP) controllers Generation3 (Cypress
Txx3xx parts).

The driver has a similar architecture that yours and it has a generic
driver to control the device and a driver for each communication bus
used to communicate with the controller. Drivers for SPI and I2C data
buses are already implemented.

The drivers are:

drivers/input/touchscreen/cyttsp_core.c
drivers/input/touchscreen/cyttsp_i2c.c
drivers/input/touchscreen/cyttsp_spi.c

This driver was original developed by Kevin for Android and used
multi-touch protocol type A. Since the hardware is able to track
contacts by hardware I added protocol type B support and cleaned the
driver to be merged on mainline.

I wonder how big is the delta between cyttsp Gen3 and cyttsp Gen4 and
if both drivers could be merged or at least refactored to reuse some
common code. I don't have the specification for any of the device
families but by looking at your code it seems that this may be
possible.

Thanks a lot and best regards,
Javier