[PATCH] input/touchscreen: add S3C24XX SoC touchscreen input driver

[Nelson Castillo]

On Tue, Oct 20, 2009 at 4:41 AM, Mark Brown
<broonie at opensource.wolfsonmicro.com> wrote:
> On Tue, Oct 20, 2009 at 03:21:17AM -0500, Nelson Castillo wrote:
>
>> Can the s3c driver send the events at full speed? (Maximum possible ADC rate?).

Yes, but in packets I think (The way I would know how to implement it).
We could try sending 2000 events per second to user-space and see what
happens :-) :-)

>> Even if it's possible I think we would monopolize the adc driver
>> needlessly because we don't need all that conversions when there is
>> not much noise. Please read on.
>
> There's currently no facility to push sample rate requests down into the
> kernel from userspace.  However, this is a good idea in general - there
> was some recent (brief) discussion of doing this on the linux-input list.

I see. It makes sense.

ATM one big difference with the kernel approach is that in the kernel
you can request the adc conversions on demand.

> Since different use cases have different sample rate requirements (such
> as the difference between handwriting recognition which can need 200
> samples/second and a simple finger operated menu which may be happy with
> 10) there's value in being able to vary the sample rate at run time.  I
> was intending to look at this shortly as part of some touchscreen driver
> development I need to do soon or perhaps someone else will pick up the
> idea, if it does get implemented then obviously tslib would also be able
> to use it here.

With a lot more points you can indeed do better filtering in users-pace.