Date: Thu, 25 Jun 2009 23:09:49 +0800
From: Alek Du <alek.du@intel.com>
To: Jani Nikula <ext-jani.1.nikula@nokia.com>
CC: LKML <linux-kernel@vger.kernel.org>, Trilok Soni <soni.trilok@gmail.com>,
       "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
       Dmitry Torokhov <dmitry.torokhov@gmail.com>,
       "ben-linux@fluff.org" <ben-linux@fluff.org>
Subject: Re: [PATCH]input: Change timer function to workqueue for gpio_keys
 driver
Message-ID: <20090625230949.53beda65@dxy.sh.intel.com>
In-Reply-To: <1245942355.20530.141.camel@jani-desktop>
References: <20090608152420.0e76c302@dxy.sh.intel.com>
	<5d5443650906121040n3f36c99eka01f5eb5274ee6ff@mail.gmail.com>
	<359ed6810906250329x70cf380cy278f23e3ebc6a829@mail.gmail.com>
	<20090625210642.432e08a5@dxy.sh.intel.com>
	<1245936693.20530.107.camel@jani-desktop>
	<20090625220826.1fa7413e@dxy.sh.intel.com>
	<1245941565.20530.134.camel@jani-desktop>
	<1245942355.20530.141.camel@jani-desktop>
Organization: Intel Corp.
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1679
Lines: 42

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.
> 
> 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/