Re: [PATCH] Input: zforce - make the interrupt GPIO optional

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Wed, Jul 29, 2015 at 08:17:10PM +0200, Heiko Stübner wrote:
> Hi Dmitry,
> 
> Am Mittwoch, 29. Juli 2015, 10:53:04 schrieb Dmitry Torokhov:
> > On Tue, Jul 28, 2015 at 11:43:20PM +0200, Heiko Stübner wrote:
> 
> [snip]
> 
> > > > > @@ -510,7 +511,18 @@ static irqreturn_t zforce_irq_thread(int irq,
> > > > > void
> > > > > *dev_id)>
> > > > > 
> > > > >  	if (!ts->suspending && device_may_wakeup(&client->dev))
> > > > >  	
> > > > >  		pm_stay_awake(&client->dev);
> > > > > 
> > > > > -	while (gpiod_get_value_cansleep(ts->gpio_int)) {
> > > > > +	while (run) {
> > > > > +		/*
> > > > > +		 * Exit the loop if either
> > > > > +		 * - the optional interrupt GPIO isn't specified
> > > > > +		 *   (there is only one packet read per ISR invocation, 
> then)
> > > > > +		 * or
> > > > > +		 * - the GPIO isn't active any more
> > > > > +		 *   (packet read until the level GPIO indicates that there 
> is
> > > > > +		 *    no IRQ any more)
> > > > > +		 */
> > > > > +		run = gpiod_get_value_cansleep(ts->gpio_int);
> > > > > +
> > > 
> > > alteratively you could simply convert to a
> > > 
> > > 	/* Run at least once, or as long as the interrupt gpio is active. */
> > > 	do {
> > > 	
> > > 		...
> > > 	
> > > 	} while(gpiod_get_value_cansleep(ts->gpio_int));
> > > 
> > > saving the additional variable run and a lot of lines, while still running
> > > at least once.
> > 
> > But I think that means that we'll try to read even if gpio is not active
> > anymore on the first iteration.
> 
> I don't think this is a possible scenario :-)
> 
> The interrupt is only used for transmission of touch-data and is pulled low as 
> long as the host hasn't fetched all touch-packages. So if nothing else except 
> the zforce-driver talks to the chip, the gpio will stay on.
> 
> And when we're entering the interrupt handler, there is at least one touch-
> data package waiting.

I see. Then please ignore me ;)

-- 
Dmitry
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