Re: [PATCH 2/2] x86: of: define irq functions to allow drivers/of/* to build on x86

Thomas Gleixner
2010-09-21T09:44:27Z

On Fri, 10 Sep 2010, Grant Likely wrote:

> On Fri, Sep 10, 2010 at 08:14:58PM +0200, Ingo Molnar wrote:
> >
> > * Grant Likely <grant.likely@secretlab.ca> wrote:
> >
> > > On Fri, Sep 10, 2010 at 06:01:51AM -0700, Andres Salomon wrote:
> > > >
> > > > - Define a stub irq_create_of_mapping for x86 as a stop-gap solution until
> > > > drivers/of/irq is further along.
> > > > - Define irq_dispose_mapping for x86 to appease of_i2c.c
> > > >
> > > > Signed-off-by: Andres Salomon <dilinger@queued.net>
> > >
> > > Applied to my test-devicetree branch. I'll need an ack from the x86
> > > maintainers before I put it into my -next branch.
> >
> > The purpose of the patch is not clear to me. What does it do and why?
>
> It allows CONFIG_OF to be enabled on x86 without a build failure.
>
> > The changelog says it's a stopgap measure - what exactly is the long
> > term plan and how long will it take?
>
> It is a stop gap because it performs a trivial direct map of an IRQ
> number in the device tree data structure to a Linux irq number. This
> works for a single IRQ controller, but falls apart when cascaded
> controller are described in the device tree. The long term plan is to
> have the drivers/of/ code handling the mapping intelligently like
> powerpc currently does.

Sounds good. We need this for other embedded x86 platforms as well and
I was looking into the powerpc code before and wondered how we can
make that generic. The question is whether this should be tied into
drivers/of/irq or just provided as an OF independent generic facility
in kernel/irq.

Thanks,

tglx