RE: ep93xx gpio interrupt debounce

["hartleys" <hartleys@xxxxxxxxxxxxxxxxxxx>]

On Wednesday, April 23, 2008 6:25 PM, Lennert Buytenhek wrote:
> > The patch below adds debouncing support to the ep93xx GPIO
interrupts.
> > 
> > Please review and let me know if it looks okay.
>
> Ah.  This looks very similar to the patch I wrote for it originally.

Well, it should. I just updated it for the new kernel ;-)

 
> And I remember now why I never submitted it for merging:
>
> > Index: src/working/linux-2.6.25/include/asm-arm/irq.h
> > ===================================================================
> > --- src.orig/working/linux-2.6.25/include/asm-arm/irq.h
2008-04-22
> > 19:57:08.000000000 -0700
> > +++ src/working/linux-2.6.25/include/asm-arm/irq.h	2008-04-22
> > 19:58:03.000000000 -0700
> > @@ -35,6 +35,7 @@
> >  #define IRQT_LOW	(__IRQT_LOWLVL)
> >  #define IRQT_HIGH	(__IRQT_HIGHLVL)
> >  #define IRQT_PROBE	IRQ_TYPE_PROBE
> > +#define IRQT_DEBOUNCE	(1 << 5)
> >  
> >  #ifndef __ASSEMBLY__
> >  struct irqaction;
>
> I'm not happy with this part -- it seems wrong to add a IRQT_* for
> something that is only used on one particular SoC.
> 
> Then again, the ->set_type() API _is_ IMHO the place where debounce
> should be handled.
> 
> So.. I don't know what to do with this, basically.

I agree adding the new IRQT_* is dicey.

But.. set_irq_type() doesn't do anything with the type parameter except
pass it to desc->chip->set_type(). Which in turn calls the ep93xx
machine specific function. The IRQT_DEBOUNCE flag is checked first,
handled, then masked off the type parameter. So when desc->status gets
set all the bits are "normal".

What about renaming IRQT_DEBOUNCE to IRQT_EP93XX_DEBOUNCE and moving the
definition to <asm/arch/irqs.h> (<asm-arm/arch-ep93xx/irqs.h> with a big
fat warning with what it's used for?

Hartley

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