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

From: Eric Miao
Date: Tue Nov 17 2009 - 22:04:04 EST


On Wed, Nov 18, 2009 at 8:22 AM, Paul Parsons <lost.distance@xxxxxxxxx> wrote:
>> Does pressure actually work as expected -- that is not inverted?
>> Because I need this patch on spitz... Âbut 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   Âts->pressure_max-Rt
> 599 Â Â 425
> 562 Â Â 462
> 588 Â Â 436
> 570 Â Â 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
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