[PATCH] parisc: make NO_IRQ 0 as it should be

[PATCH] parisc: make NO_IRQ 0 as it should be

[Alan Cox]

From: Alan Cox <alan@linux.intel.com>

PA-RISC doesn't use a real IRQ 0 and James says

"To be honest, we don't care very much.  Parisc interrupts are cascading
and mostly software assigned (except our EIEM which we keep internal).
We use a base offset at 16 or 64 (depending on GSC presence or not) so
IRQs 0-15 aren't legal on parisc either (we frob some of the hard coded
ISA interrupts on the WAX eisa bus).

We use NO_IRQ as an IRQ assignment error return and that's about it (and
that error shouldn't ever really occur)."

Signed-off-by: Alan Cox <alan@linux.intel.com>
---

 arch/parisc/include/asm/irq.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)


diff --git a/arch/parisc/include/asm/irq.h b/arch/parisc/include/asm/irq.h
index 1073599..fcf6edd 100644
--- a/arch/parisc/include/asm/irq.h
+++ b/arch/parisc/include/asm/irq.h
@@ -10,7 +10,7 @@
 #include <linux/cpumask.h>
 #include <asm/types.h>
 
-#define NO_IRQ		(-1)
+#define NO_IRQ		0
 
 #ifdef CONFIG_GSC
 #define GSC_IRQ_BASE	16

Re: [PATCH] parisc: make NO_IRQ 0 as it should be

[James Bottomley]

On Tue, 2011-12-06 at 11:24 +0000, Alan Cox wrote:
> From: Alan Cox <alan@linux.intel.com>
> 
> PA-RISC doesn't use a real IRQ 0 and James says
> 
> "To be honest, we don't care very much.  Parisc interrupts are cascading
> and mostly software assigned (except our EIEM which we keep internal).
> We use a base offset at 16 or 64 (depending on GSC presence or not) so
> IRQs 0-15 aren't legal on parisc either (we frob some of the hard coded
> ISA interrupts on the WAX eisa bus).
> 
> We use NO_IRQ as an IRQ assignment error return and that's about it (and
> that error shouldn't ever really occur)."
> 
> Signed-off-by: Alan Cox <alan@linux.intel.com>
> ---
> 
>  arch/parisc/include/asm/irq.h |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> 
> diff --git a/arch/parisc/include/asm/irq.h b/arch/parisc/include/asm/irq.h
> index 1073599..fcf6edd 100644
> --- a/arch/parisc/include/asm/irq.h
> +++ b/arch/parisc/include/asm/irq.h
> @@ -10,7 +10,7 @@
>  #include <linux/cpumask.h>
>  #include <asm/types.h>
>  
> -#define NO_IRQ		(-1)
> +#define NO_IRQ		0

Unfortunately, it's not quite as simple as this.  There's one use of
NO_IRQ as an error return in the EIEM code, which returns the internal
line number (which run 0-32/64 ... I'll have to fix those before this
can be done.

James