Support for multiple MSI interrupts on MPC8377

[Giffel, Brad]

A single MSI interrupt it is then.

	Thanks,
	- Brad


-----Original Message-----
From: Michael Ellerman [mailto:michael at ellerman.id.au] 
Sent: Wednesday, November 02, 2011 10:51 PM
To: Giffel, Brad
Cc: linuxppc-dev at lists.ozlabs.org; Matthew Wilcox
Subject: Re: Support for multiple MSI interrupts on MPC8377

On Wed, 2011-11-02 at 16:02 -0500, Giffel, Brad wrote:
> I'm working a project using a Spartan 6 FPGA with a PCIe interface and
> MSI interrupts.  I want to use multiple MSI interrupts (MSI-X is not
> supported in the FPGA PCIe core) but the current Linux distribution
> (3.0.8) prevents that (lines 23 to 25 in arch/powerpc/kernel/msi.c).
> 
>  
> 
> What's the story here?  Is the code in place but not tested?  I tried
> commenting out those lines but a request_irq() called failed for the
> second interrupt requested.  Am I wasting my time here?  Should I
> re-architect to use a single MSI interrupt?

The short and easy answer is you should use a single MSI interrupt.

There is some code in place to support multiple MSI, but only in the
generic code (drivers/pci/msi.c), and I'm not sure if it's complete.
There is no arch support, for any arch AFAIK, and certainly not for
powerpc.

cheers