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

Jani Nikula
2009-06-25T15:06:25Z

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?

> 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.

BR,
Jani.