Hi
Armin Kuster wrote:
> "David M?ller (ELSOFT AG)" wrote:
>
>>Hello
>>
>>The attached patch fixes the following issues:
>>
>> - arch/ppc/kernel/ppc4xx_pic.c
>> fixed constant in ppc405_pic_get_irq()
>> (should be NR_AIC_IRQS as in ppc403_pic_get_irq())
>>
>
> David,
>
> include/asm-ppc/irq.h
> NR_IRQS = (NR_AIC_IRQS + NR_BOARD_IRQS) and was defined to allow
> cascading UIC's.
> NR_BOARD_IRQS is defined in some of the board files and its default is
> in include/asm-ppc/ibm4xx.h
>
> So i don't see the need to patch that file but the others look fine.
>
>
Exactly, NR_IRQS is the the total number of irqs possible in the system
as this number of irqs is reserved in the irq_desc table.
For example, we have a system with a PPC405GP and an additional PC like 8259 PIC
pair, we have NR_AIC_IRQS (32) + NR_BOARD_IRQS (16) = NR_IRQS (48).
In ppc405_pic_get_irq() the following code is executed:
irq = 32 - ffs(bits);
if (irq == NR_IRQS)
irq = -1;
return(irq);
with NR_IRQS equal 48 the condition is never true !
This results in an endless while-loop in do_IRQ() in arch/ppc/kernel/irq.c
Either this or my understanding how things are working is totally wrong. ;-)
Additionally, i don't see me why ppc403_pic_get_irq() is using NC_AIC_IRQS while
ppc405_pic_get_irq() is using NR_IRQS. Shouldn't they be "symmetric".
Dave
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