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Date: Mon, 7 Jun 2010 12:30:11 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Esben Haabendal <eha@doredevelopment.dk>
Subject: Re: [PATCH 2/2] gpio: pca953x: add powerpc irq support
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On Mon, 7 Jun 2010, Esben Haabendal wrote:
> On Mon, 2010-06-07 at 01:39 +0200, Thomas Gleixner wrote: 
> > On Fri, 4 Jun 2010, Esben Haabendal wrote:
>
> > > @@ -120,6 +124,10 @@ static int pca953x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
> > >  	chip = container_of(gc, struct pca953x_chip, gpio_chip);
> > >  
> > >  	reg_val = chip->reg_direction | (1u << off);
> > > +
> > > +	if (reg_val == chip->reg_direction)
> > > +		return 0;
> > > +
> > 
> >  This is an optimization of its own value.
> 
> Yes, but is need to avoid doing I2C work from irq_chip map().

Still it should be a separate patch, that's all I said. 

It can be documented that it is also necessary to support powerpcs
virq thing if at all.

> > 3) it breaks the driver. See http://lkml.org/lkml/2010/6/6/177 for a
> >    detailed explanation
> 
> I believe there is still a few things that needs to be discussed before
> that is closed.

Not with me. Period.

> > 4) the virq/powerpc churn is horrible and I bet there are sane ways to
> >    solve this, but it leave this to the powerpc experts.
> 
> Do you suggest that a seperate pca953x driver should be implemented for
> powerpc?  (I guess not).  Or do you say that the who irq handling in
> powerpc should be changed?
> 
> There must be an acceptable way to extend pca953x.c for the powerpc virq
> handling and get it accepted in the kernel.

Yes, there certainly is. I just think that there are cleaner ways,
that's why I defered that to the powerpc wizards.

Thanks,

	tglx