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

["Heiko Stübner" <heiko.stuebner@bq.com>]

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.


> So maybe we need to factor out the body
> and do:
> 
> 	if (!ts->gpio_int)
> 		zforce_report_data(...)
> 	else
> 		while (gpiod_get_value_cansleep(ts->gpio_int))
> 			zforce_report_data(...);
> 
> Or we could install 2 different interrupt handlers, depending on the
> presence of interrupt gpio.


Heiko
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