A touchscreen driver has been posted upstreams

Nelson Castillo arhuaco at freaks-unidos.net
Tue Nov 24 18:04:58 CET 2009

On Tue, Nov 24, 2009 at 10:43 AM, Werner Almesberger
<werner at openmoko.org> wrote:
> Nelson Castillo wrote:
>> What I understood from this thread is that filtering has to be done in
>> user-space and that drivers should send unfiltered sets of points at a
>> higher rate.
> ... or that you (or someone) has to prove clearly that this is one
> of the things you can't do properly in user space, e.g., because
> the processing required would exceed the systems's capabilities.

Sure. I'm starting to think the tslib approach is more flexible. For
instance I see the current averaging in the upstream driver as a way
to lose information we need, and someone else might think the same for
the filtering we're doing if the TS is needed for something else
(handwriting for instance). Changing the kernel for different uses
doesn't seem to be right. Right now we optimized for reliable clicks
(in the OM tree).

> Of course, and this is a bit catch 22, the best way to prove this
> is to try to make it work in user space, do all the optimizations
> and improvements on the kernel side that may be necessary to help
> user space work better and more efficiently, and then see if the
> results are acceptable.

The main problem now is that there is no way from userpace to
communicate back to the kernel. But this might not be needed if it's
OK to lose some computing power (not much I guess).

I'd like to test soon (I'm running with something here but I might
find the time).

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