interrupt framework

[Ian Lepore]

On Fri, 2015-01-16 at 08:34 -0700, Warner Losh wrote:
> > On Jan 16, 2015, at 5:03 AM, Andrew Turner <andrew at fubar.geek.nz> wrote:
> > 
> > On Fri, 16 Jan 2015 12:44:22 +0100
> > Svatopluk Kraus <onwahe at gmail.com> wrote:
> > ...
> >> It's just a few things from quick look now which are different in our
> >> design. However, my intention is not read our code on behalf of you. I
> >> still think that our design is more general mainly and can serve for
> >> interrupt controllers better.
> > 
> > I was asking on the differences as I'm already in the process of
> > importing the arm_intrng project branch as I need something like it on
> > arm64. It is also based on the same code from Jakub and Ian, I haven't
> > looked at changing the design, just cleaning up the code to import into
> > head.
> > 
> > I would be happy to merge your code instead, along with my existing
> > cleanups, however I would need to know why I should spend time on it as
> > opposed to the current development branch. If we do decide to with your
> > change I would like to import it into the arm_intrng project branch
> > first to assist the import into head.
> 
> My first look at Svatopluk’s code and summaries, on its surface it seems
> to be a simpler, more generalized and more effective design than intern.
> It avoids some additional overhead that’s always troubled me about intern
> that I’ve not had the time to make good suggestions to overcome. It looks
> (again on its surface) easier to bring to all the architectures as well.
> 
> I haven’t tried to use the code so I can’t comment on its stability. So of course
> I can’t measure the differences in interrupt latencies between the two. Both of
> these factors would be the kind of data that would help drive the decision of which
> one to adapt.
> 
> Warner

I haven't looked at Svata's work recently, but in general he started
with the same sources that are now in the intrng branch and finished
work I was in the middle of (redoing IPI stuff) when I had to set it
aside.  Based on other work done recently by Svata and Michal, I can
only imagine that they've improved on Jakub's and my earlier effort.

My main concern for importing anything (Svata's version or the current
intrng branch) is for the Marvell code.  It's the one that's a bit
different than other modern arm systems, for example it's the reason we
had the somewhat strange design for handling IPIs in the current code.
Unfortunately, I think none of us have hardare for testing except the
folks at Semihalf.

-- Ian