Re: [PATCH] hx4700: fix hx4700 touchscreen pressure values

Eric Miao
2009-11-18T03:03:53Z

On Wed, Nov 18, 2009 at 8:22 AM, Paul Parsons <lost.distance@yahoo.com> wrote:
>> Does pressure actually work as expected -- that is not inverted?
>> Because I need this patch on spitz...  but it may break your
>> machine...
>
> You are right, the pressure values were being inverted on my hx4700.
> Pressing hard generates somewhat lower Rt values than pressing lightly.
>
> Since typical hx4700 Rt values are close to (pressure_max/2) anyway,
> the inverted and non-inverted values were not very different.
> For example:
>
> Rt      ts->pressure_max-Rt
> 599     425
> 562     462
> 588     436
> 570     454
>
> So by all means submit your ads7846.c patch; it will not break hx4700.
>

Is this generically true that the pressure is always inverted? Otherwise
a platform specific field indicating this would be the better way to go.

- eric