On Thu, 1 Dec 2011 13:47:26 +0800
Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote:
> On Wed, Nov 30, 2011 at 10:34:18AM +0800, Feng Tang wrote:
> > On Tue, 29 Nov 2011 17:23:10 +0800
> > Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote:
> >
> > > On Tue, Nov 29, 2011 at 04:12:58PM +0800, Feng Tang wrote:
> > > > This originates from a patch in Meego IVI kernel with the name
> > > > linux-2.6.37-connext-0027-tsc2007.patch
> > > > There is no author info excepte a line "From MeeGo
> > > > <kernel@xxxxxxxxx>"
> > > >
> > > > When integrating tsc2007 on Intel IVI platform, there are a lot
> > > > of noise data whose z1 value is around 10 which is not a sane
> > > > "z1". So add a "z1_low_threshhold" to filter those nosie data,
> > > > to make the device work properly.
> > >
> > > Sounds like a task for userspace to ignore pressure that is too
> > > low. Bonus points for making it configurable so user can adjust
> > > sensitivity.
> >
> > Actually, there is one more point :), without this patch, the
> > driver won't work on our platforms.
> >
> > The tsc2007_soft_irq will keep reading the input data unless there
> > is no valid pressure data. In our case, those noise data will be
> > seen as valid data during tsc2007_calculate_pressure(), and the
> > tsc2007_soft_irq will run endlessly.
>
> Even if we add the pressure threshold would not that noise cause
> endless stream of interrupts?
No, there is no endless interrupts for tsc2007. Without the z1
threshold, the while circle in tsc2007_soft_irq will run endlessly
as the noise data will be seen as a valid data:
rt = tsc2007_calculate_pressure(ts, &tc);
if (rt == 0 && !ts->get_pendown_state) {
/*
* If pressure reported is 0 and we don't have
* callback to check pendown state, we have to
* assume that pen was lifted up.
*/
break;
}
With the z1 threshold check, the rt will be 0 for noise data, and the
code flow broke out.
>
> Also, what kind of z2 is reported with low z1? And do you implement
> get_pendown_state()?
z2 seems normal as some data between 3000-4000. We don't have a
get_pendown_state().
Thanks,
Feng
>
> Thanks.
>
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