Re: [PATCH v2 1/7] ARM: mmp: parse irq from DT

From: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
To: Haojian Zhuang <haojian.zhuang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org,
	devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
	Haojian Zhuang
	<haojian.zhuang-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>,
	eric.y.miao-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	alan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org
Subject: Re: [PATCH v2 1/7] ARM: mmp: parse irq from DT
Date: Mon, 1 Aug 2011 15:10:36 +0100	[thread overview]
Message-ID: <20110801141036.GA21627@ponder.secretlab.ca> (raw)
In-Reply-To: <CAN1soZxX6EBRPvzV_00njioBn1NfiAbLBoD7EYc-wV-uQM_VoQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Mon, Aug 01, 2011 at 10:47:06AM +0800, Haojian Zhuang wrote:
> On Sat, Jul 30, 2011 at 12:36 AM, Grant Likely
> <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> wrote:
> >> diff --git a/arch/arm/mach-mmp/common.h b/arch/arm/mach-mmp/common.h
> >> index ec8d65d..1c563c2 100644
> >> --- a/arch/arm/mach-mmp/common.h
> >> +++ b/arch/arm/mach-mmp/common.h
> >> @@ -6,3 +6,4 @@ extern void timer_init(int irq);
> >>
> >>  extern void __init icu_init_irq(void);
> >>  extern void __init mmp_map_io(void);
> >> +extern void __init mmp_init_intc(void);
> >> diff --git a/arch/arm/mach-mmp/include/mach/irqs.h b/arch/arm/mach-mmp/include/mach/irqs.h
> >> index a09d328..65ec176 100644
> >> --- a/arch/arm/mach-mmp/include/mach/irqs.h
> >> +++ b/arch/arm/mach-mmp/include/mach/irqs.h
> >> @@ -224,6 +224,6 @@
> >>
> >>  #define IRQ_BOARD_START                      (IRQ_GPIO_START + IRQ_GPIO_NUM)
> >>
> >> -#define NR_IRQS                              (IRQ_BOARD_START)
> >> +#define NR_IRQS                              0
> >
> > Why is NR_IRQs getting changed?  I think this will break
> > !CONFIG_SPARSE_IRQS, and it shouldn't be necessary for this
> > conversion.
> >
> If CONFIG_SPARSE_IRQ is enabled, arch_probe_nr_irqs() returns NR_IRQS in arm.
> It results registering NR_IRQS in early_irq_init(). If NR_IRQS is 200,
> 200 irqs are
> registered in early_irq_init(). It's not my requirement. What I need
> is registering irq
> from DT.
> 
> So I have to define NR_IRQS to 0. And CONFIG_SPARSE_IRQS is always enabled
> in ARCH_MMP. So it's selected in Kconfig by default.

My point is, that applying this patch will break anyone depending on
non-DT mach-mmp support.  I'm completely fine with you doing so, but
you need to be extra careful that it is done in a bisectable way.  At
no point in the commit series should the kernel be unable to build a
working mmp image.

g.