Re: [PATCH v3 3/8] drivers:input:tsc2007: add iio interface to read external ADC input, temperature and raw conversion values

From: H. Nikolaus Schaller
Date: Sat Sep 24 2016 - 13:51:24 EST

Hi Dmitry,

> Am 24.09.2016 um 19:44 schrieb Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>:
> On Sat, Sep 24, 2016 at 10:07 AM, H. Nikolaus Schaller
> <hns@xxxxxxxxxxxxx> wrote:
>> Hi Jonathan,
>>> Am 24.09.2016 um 18:07 schrieb Jonathan Cameron <jic23@xxxxxxxxxx>:
>>> On 23/09/16 13:41, H. Nikolaus Schaller wrote:
>>>> The tsc2007 chip not only has a resistive touch screen controller but
>>>> also an external AUX adc imput which can be used for an ambient
>>>> light sensor, battery voltage monitoring or any general purpose.
>>>> Additionally it can measure the chip temperature.
>>>> This extension provides an iio interface for these adc channels
>>>> in addition to the raw x, y, z values and the estimated touch
>>>> screen resistance. This can be used for debugging or special
>>>> applications.
>>> I'm unconvinced that exposing the touch related channels is terribly
>>> useful.
>> Mostly for debugging of if someone wants to do a (better) touch detection


>> in user space.
> For that we should probably export data as a heat map via V4L2
> interface, similarly to what Nick Dyer did for Synaptics and Atmel
> drivers (albeit their heatmap functions are too slow for real
> processing and only suitable for debug/validation).

Sorry for my ignorance, but what is a heat map?
Does it allow to cat /sys/bus/something the raw values?

And why introduce another interface if we already get the iio that
easily reports such values by just adding more channels and some
lines of code?