Re: [Power.org:parch] Re: RFC: proposal to extend the open-pic interrupt specifierdefinition

[Scott Wood <scottwood-KZfg59tc24xl57MIdRCFDg@public.gmane.org>]

Grant Likely wrote:
> On Wed, Jan 13, 2010 at 7:19 AM, Yoder Stuart-B08248
> <B08248-KZfg59tc24xl57MIdRCFDg@public.gmane.org> wrote:
>>> It does not sound sane or
>>> particularly parseable to stuff it into bitfields within the second
>>> cell.
>> I think it is somewhat sane compared to the alternatives.  The
>> second cell encodes information about the interrupt source.  Allowing
>> some of those bits to encode information besides level/sense
>> doesn't seem that difficult.
> 
> Not difficult.  Ugly, unnecessary, and sounds like a premature optimization.

It is not optimization, but functionality.

>>> Users have enough trouble parsing irq specifiers as is.  It makes me
>>> nervous to see even more complicated irq specifiers being devised.
>> Yes, they become slightly more complicated, but the complexity needs to
>> go somewhere.
> 
> Then at the very least do it as separate cells.  Carving cells into
> multiple fields is pretty ugly when cells are cheap.

That means that all the interrupt specifiers in an existing tree have to 
be updated with the larger numer of cells whenever such an interrupt is 
added, since #interrupt-cells applies globally to the MPIC interrupt 
domain.  It's unnecessary churn.

-Scott