Hi Martin,

I am aware of tslib. However, I was not able to find something like
that on Android Systems.

Thanks,
Sriram

On Fri, May 19, 2017 at 6:24 PM, Martin Kepplinger
[off-list ref] wrote:

On 2017-05-18 11:21, Sriram V wrote:

quoted

Hi,

I wanted to find out how does touch calibration works? Is this
something that is taken care in the userspace?
Unfortunately, my device does not have a Write Interface. I have read
the values from the device but can't do i2c writes to the device.
I also wanted to find out how touch screen calibration is done in
Android systems.

Calibration is linear transformation of coordinate values. Usually this
is not a driver's work. The driver should make sure userspace can talk
in "evdev" sync frames.

It is usually done in userspace, by an X.org input "driver" for example.
At least I think xf86-input-evdev does some calibration.

For touchscreen devices, especially in embedded and if people need more
filters than linear transormation, tslib ( http://tslib.org ) is often
used for calibration. The one tslib module doing calibration is called
"linear" and can be configured (the actual calibration process) with a
graphical framebuffer application, ts_calibrate which is part of tslib.

                       martin

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