linux-kernel - Re: [PATCH 3/9] irq: convert generic-chip to use irq

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Message-ID: <20111215140827.GB2963@S2100-06.ap.freescale.net>
Date:	Thu, 15 Dec 2011 22:08:28 +0800
From:	Shawn Guo <shawn.guo@...escale.com>
To:	Rob Herring <robherring2@...il.com>
CC:	Kevin Hilman <khilman@...com>, Kukjin Kim <kgene.kim@...sung.com>,
	Tony Lindgren <tony@...mide.com>,
	Linus Walleij <linus.ml.walleij@...il.com>,
	<devicetree-discuss@...ts.ozlabs.org>,
	<linux-kernel@...r.kernel.org>,
	Rob Herring <rob.herring@...xeda.com>,
	Barry Song <baohua.song@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 3/9] irq: convert generic-chip to use irq_domain

On Thu, Dec 15, 2011 at 07:39:37AM -0600, Rob Herring wrote:
> On 12/14/2011 11:55 PM, Shawn Guo wrote:
> > On Thu, Dec 15, 2011 at 01:25:20PM +0800, Shawn Guo wrote:
> >> On Wed, Dec 14, 2011 at 09:28:52AM -0600, Rob Herring wrote:
> >>> From: Rob Herring <rob.herring@...xeda.com>
> >>>
> >>> Add irq domain support to irq generic-chip. This enables users of
> >>> generic-chip to support dynamic irq assignment needed for DT interrupt
> >>> binding. Users must be converted to use irq_data.hwirq for determining
> >>> local interrupt numbers rather than using the Linux irq number.
> >>>
> >>> irq_base is kept for now as there are a few users of it. Once they
> >>> are converted to use the irq domain, it can be removed.
> >>>
> >>> Signed-off-by: Rob Herring <rob.herring@...xeda.com>
> >>> Cc: Thomas Gleixner <tglx@...utronix.de>
> >>> ---
> >>
> >> Tested-by: Shawn Guo <shawn.guo@...aro.org>
> >>
> > Sorry, I have to take that tag back after I correct my test setup.
> > It does not work for imx5 TZIC case, because the following change
> > I suggested before is missed.
> > 
> > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> > index eb763f7..2a2aac1 100644
> > --- a/kernel/irq/irqdomain.c
> > +++ b/kernel/irq/irqdomain.c
> > @@ -39,7 +39,7 @@ void irq_domain_add(struct irq_domain *domain)
> >                         return;
> >                 }
> >                 d->domain = domain;
> > -               d->hwirq = hwirq;
> > +               d->hwirq = hwirq - domain->hwirq_base;
> 
> This is a problem. It entirely defeats the point of hwirq_base and it
> would break the GIC. We need to fix this in the generic irq chip.
> 
Actually I do not quite understand why we need to make the following
change all over generic-chip.c.

-       u32 mask = 1 << (d->irq - gc->irq_base);
+       u32 mask = 1 << d->hwirq;

Though d->irq is the Linux irq number, "d->irq - gc->irq_base" is
really just what we need here.

-- 
Regards,
Shawn

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