Re: [PATCH]input: Change timer function to workqueue for gpio_keys driver

Alek Du
2009-06-25T15:14:57Z

On Thu, 25 Jun 2009 23:05:55 +0800
Jani Nikula <ext-jani.1.nikula@nokia.com> wrote:

> On Thu, 2009-06-25 at 16:52 +0200, Jani Nikula wrote:
> > On Thu, 2009-06-25 at 16:08 +0200, ext Alek Du wrote:
> > > If you schedule the timer when you decide it "stabilized", the final gpio_get_value()
> > > could still return 0 in the timer handler, if the key released at that time. So your previous
> > > "stabilized" state is useless.
> >
> > True, gpio_keys_report_event should also compare the value to the
> > previous state and bail out if it's unchanged. Something along the lines
> > of:
> >
> > @@ -46,6 +46,10 @@ static void gpio_keys_report_event(struct work_struct *work)
> > unsigned int type = button->type ?: EV_KEY;
> > int state = (gpio_get_value(button->gpio) ? 1 : 0) ^ button->active_low;
> >
> > + if (state == bdata->state)
> > + return;
> > + bdata->state = state;
>
> Actually scrap that, the input layer already ignores events with no
> state changes, right?
>
Yes, correct. I just want to reply your previous mail, but seems you find that. :-)
> > Debouncing should also completely ignore a single spike shorter than
> > debounce_interval. Admittedly gpio-keys was flawed, but please consider
> > a change like above which should fix that.
>
> Same here, gpio-keys did ignore spikes shorter than debounce_interval.
>
Yes, sending first state 0 to input layer does nothing wrong.
>
> BR,
> Jani.
>
>