How do I make Xglamo read directly from the touchscreen?

Carsten Haitzler (The Rasterman) raster at
Sun Dec 28 00:51:35 CET 2008

On Fri, 26 Dec 2008 22:16:32 -0500 "Nelson Castillo" <nelsoneci at>

> On Fri, Dec 26, 2008 at 9:05 PM, Werner Almesberger <werner at>
> wrote:
> > Nelson Castillo wrote:
> >> A feature I would say :-)  This is even better than what we have in the
> >> stable kernel because we discard noise. Sometimes the last few events
> >> get discarded because they do not provide reliable data, for instance
> >> because not much pressure is applied.
> >
> > Discarding bogus data is obviously a good thing. I was more curious
> > about why you collect enough data to start the filter and only then
> > check if you're going to throw it all away anyhow. This may not make
> > much of a difference in terms of performance, but the way you
> > described it, this sounded like a feature.
> :-) Actually you might get enough data to report a point that makes
> sense. And often you find out that even when the hardware reports
> pen down, the last few points are not reliable.
> > By the way, is tslib obliged to deliver a point for each incoming
> > event ?
> It is not. For instance, I sent the skip plug-in (no longer needed by
> us) earlier
> this month.
> I got no feedback BTW...
> > If not, then it could do the same kind of discarding of bad
> > events, couldn't it ?
> Sort of. With our current driver (with a timer) we can deliver events
> each 5 milliseconds (HZ = 200). We would have to deliver chunks of
> them (let's say 8 points each 5 milliseconds...). It gets a little weir when
> we delay reporting the 'up' event. I don't know if this can be done in tslib.
> You have a function there that blocks waiting for input there, I don't know if
> you can somehow use a timeout with it like you do with select(2).
> The implementation would not be equivalent, it would be similar.
> IMHO the only one that can be just the same in kernel and in user-space
> is the linear filter because the other filters give feedback to the interrupt
> function.

all in all - the point here isn't to remove tslib - just turn off
tslib's filtering! keep it. just disable what you don't need anymore!

------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler)    raster at

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