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

[Haojian Zhuang <haojian.zhuang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Mon, Aug 1, 2011 at 10:10 PM, Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> wrote:
> 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.
>
>

Since .nr_irqs property is assigned in machine descriptor of brownstone.c or
ttc_dkb.c, nr_irqs equals to machine_desc->nr_irqs (arch/arm/kernel/irq.c).

Even NR_IRQS is defined as 0, machine_desc->nr_irqs can help us to
pre-allocate irq numbers while CONFIG_OF isn't defined.

So it's not an issue in ARCH_MMP. And I tested it that everything is well.

Thanks
Haojian