Hi Dmitry,
On Thu, 1 Dec 2011 16:45:24 +0800
Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote:
> > >
> > > 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.
>
> What I meant is with the threshold check we'll break out of the ISR
> but why won't IRQ be raised again?
The IRQ will be fired again after we exist the tsc2007_soft_irq in my
test, as I re-enable the irq before existing the code.
>
> >
> > >
> > > 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().
>
> OK, there is max_rt platform parameter. I think we should employ it
> instead and break out if we get several incorrect samples in a row.
> Too bad you do not have a dedicate method.
>
No, the max_rt won't help here, if the rt > max_rt, it won't break the
while loop, but just issue a warning message
if (rt <= ts->max_rt) {
.......
} else {
/*
* Sample found inconsistent by debouncing or pressure is
* beyond the maximum. Don't report it to user space,
* repeat at least once more the measurement.
*/
dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
}
Thanks,
Feng
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