Re: [PATCH] input: make gpio-keys use IRQF_SHARED

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

On Tue, Sep 22, 2009 at 05:14:22PM +0200, Ferenc Wagner wrote:
> Dmitry Torokhov <dmitry.torokhov@gmail.com> writes:
> 
> > On Wed, Sep 16, 2009 at 07:03:18PM +0400, Dmitry Eremin-Solenikov wrote:
> >> There is nothing that disallows gpio-keys to share it's IRQ line
> >> w/ other drivers. Make it use IRQF_SHARED in request_irq().
> >> 
> >> An example of other driver with which I'd like to share IRQ line
> >> for GPIO buttons is ledtrig-gpio.
> >> 
> >> Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
> >> ---
> >>  drivers/input/keyboard/gpio_keys.c |    1 +
> >>  1 files changed, 1 insertions(+), 0 deletions(-)
> >> 
> >> diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
> >> index efed0c9..9fc2fab 100644
> >> --- a/drivers/input/keyboard/gpio_keys.c
> >> +++ b/drivers/input/keyboard/gpio_keys.c
> >> @@ -147,6 +147,7 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
> >>  		}
> >>  
> >>  		error = request_irq(irq, gpio_keys_isr,
> >> +				    IRQF_SHARED |
> >>  				    IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
> >>  				    button->desc ? button->desc : "gpio_keys",
> >>  				    bdata);
> >
> > How will you determine which device generated the interrupt? Because you
> > can't return IRQ_HANDLED unconditionally and expect both devices work
> > reliably.
> 
> It would be possible, but commit
> da0d03fe6cecde837f113a8a587f5a872d0fade0 states that:
> 
>     The gpio_get_value function may sleep, so it should not be called in a
>     timer function.
> 
> But I don't see why it could sleep, is that really the case?

There are things like i2c gpio extenders that require access to slow
buses and can't sleep.

>  Because
> that makes acknowledging the interrupt very hard.  Actually, I need
> and tested interrupt sharing.  What are the "cansleep wrappers" in
> asm-generic/gpio.h if these function can sleep as well?  I'd be
> grateful for some explanation.  Also, commit
> 57ffe9d539e0eb741bb9ca8f2834d210e70ee2e3 removed the possibility of
> telling apart different keys, so that should be reverted during the
> process.  I already asked Uwe Kleine-König about the whys, but didn't
> get a reply.

I don't see why you say that... You request IRQ per button and you get
that button structure as argument in the interrupt handler.

-- 
Dmitry
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