Questions on interrupt vector assignment on MPC8641D

[Scott Wood]

On Sat, 9 Oct 2010 10:52:49 -0500
<david.hagood at gmail.com> wrote:

> First of all - where is all of this documented? There seems to be a great
> deal of "oral tradition" type knowledge here, but is any of it actually
> written down somewhere? (see below for examples)

Documentation/powerpc/dts-bindings/fsl/mpic.txt

Plus the chip manual, for the register offsets.

> > On Thu, 7 Oct 2010 15:12:26 -0500
> > This is asking for the 256th specifier in the interrupts property in
> > the mpic node -- not what you want.
> 
> That was from some of the previous emails in this thread.
> 
> > Ideally you would have a node for your device with an interrupt
> > specifier that you could look up with irq_of_parse_and_map().
> 
> OK, and how do these devices come into being? From what I can tell, they
> are defined by uBoot, and if uBoot doesn't define it, then you are out of
> luck.

More commonly they're statically defined in the dts file, not
dynamically created by u-boot.

If it's not in the dts, add it.  If for whatever reason that's not an
option, you can use irq_create_mapping() as I mentioned in the previous
e-mail.

> * A set of APIs (irq_of_parse_and_map(), irq_create_mapping) that were,
> for all intents, undocumented (just "here's the parameters", no
> description of when and how to use them), that took a ???? and returned a
> ???? (because, with the documentation I had, that's basically all I could
> say about them).

Yes, there are many parts of the kernel that could use better
documentation.

> > BTW, the MSIs are already described in an msi node in the device tree.
> 
> As I stated previously - not that I can see.

What board are you using?  What kernel?

If you grep arch/powerpc/boot/dts for msi in a reasonably recent kernel
you should find msi nodes.

> It may be they are defined in PCI Root Complex mode, 

No, it's a separate node.

-Scott