linux/Documentation/input/devices/edt-ft5x06.rst
Martin Kepplinger aa3d4409b6 Input: edt-ft5x06 - increase allowed data range for threshold parameter
The datasheet and application note does not mention an allowed range for
the M09_REGISTER_THRESHOLD parameter. One of our customers needs to set
lower values than 20 and they seem to work just fine on EDT EP0xx0M09 with
T5x06 touch.

So, lacking a known lower limit, we increase the range for thresholds,
and set the lower limit to 0. The documentation is updated accordingly.

Signed-off-by: Schoefegger Stefan <stefan.schoefegger@ginzinger.com>
Signed-off-by: Manfred Schlaegl <manfred.schlaegl@ginzinger.com>
Signed-off-by: Martin Kepplinger <martin.kepplinger@ginzinger.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
2017-05-22 17:22:50 -07:00

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EDT ft5x06 based Polytouch devices
----------------------------------
The edt-ft5x06 driver is useful for the EDT "Polytouch" family of capacitive
touch screens. Note that it is *not* suitable for other devices based on the
focaltec ft5x06 devices, since they contain vendor-specific firmware. In
particular this driver is not suitable for the Nook tablet.
It has been tested with the following devices:
* EP0350M06
* EP0430M06
* EP0570M06
* EP0700M06
The driver allows configuration of the touch screen via a set of sysfs files:
/sys/class/input/eventX/device/device/threshold:
allows setting the "click"-threshold in the range from 0 to 80.
/sys/class/input/eventX/device/device/gain:
allows setting the sensitivity in the range from 0 to 31. Note that
lower values indicate higher sensitivity.
/sys/class/input/eventX/device/device/offset:
allows setting the edge compensation in the range from 0 to 31.
/sys/class/input/eventX/device/device/report_rate:
allows setting the report rate in the range from 3 to 14.
For debugging purposes the driver provides a few files in the debug
filesystem (if available in the kernel). In /sys/kernel/debug/edt_ft5x06
you'll find the following files:
num_x, num_y:
(readonly) contains the number of sensor fields in X- and
Y-direction.
mode:
allows switching the sensor between "factory mode" and "operation
mode" by writing "1" or "0" to it. In factory mode (1) it is
possible to get the raw data from the sensor. Note that in factory
mode regular events don't get delivered and the options described
above are unavailable.
raw_data:
contains num_x * num_y big endian 16 bit values describing the raw
values for each sensor field. Note that each read() call on this
files triggers a new readout. It is recommended to provide a buffer
big enough to contain num_x * num_y * 2 bytes.
Note that reading raw_data gives a I/O error when the device is not in factory
mode. The same happens when reading/writing to the parameter files when the
device is not in regular operation mode.