request_irq return errno 38

[Scott Wood]

On Wed, Feb 11, 2009 at 03:43:26PM +0530, Vijay Nikam wrote:
> Ok ... so that means if I am writing driver for any device I need to
> take care of this mapping ? ? ? I mean I should use virq ? ? ?
> 
> I read in LDD book,

The problem with dead-tree books on a volatile subject is they quickly
get out of date.

> they give directly irq no. they have given parallel port example, here
> they have set or said irq no. defaults to 7 and they have not done any
> irq_mapping so what is the difference ? ? ? I mean how I should know
> when to use irq_mapping and when not ? ? ?

That's for legacy ISA interrupts.  On powerpc, you generally will want to
get the interrupt from the device tree using irq_of_parse_and_map().

-Scott