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Date: Wed, 29 Jun 2011 10:22:54 -0500
From: Ayman El-Khashab <ayman@elkhashab.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH v4]PPC4xx: Adding PCI(E) MSI support
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Cc: linuxppc-dev@ozlabs.org, Rupjyoti Sarmah <rsarmah@amcc.com>,
	rsarmah@apm.com, linux-kernel@vger.kernel.org
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On Wed, Jun 29, 2011 at 09:15:28AM +1000, Benjamin Herrenschmidt wrote:
> On Tue, 2011-06-28 at 17:31 -0500, Ayman El-Khashab wrote:
> > > > +static int ppc4xx_setup_pcieh_hw(struct platform_device *dev,
> > > > +                            struct resource res, struct
> > ppc4xx_msi *msi)
> > > > +{
> > > > +
> > 
> > <snip>
> > 
> > > > +
> > > > +   msi->msi_dev = of_find_node_by_name(NULL, "ppc4xx-msi");
> > > > +   if (msi->msi_dev)
> > > > +           return -ENODEV;
> > 
> > This does not look correct. I guess it should probably read 
> > 
> > if (!msi->msi_dev) .....
> 
> Indeed, that looks bogus. Rupjyoti, please test and send fixes if
> necessary, obviously this code has not been tested.
> 
> This is not part of the bits I fixed up so I looks to me like the
> original patch was wrong (and thus obviously untested !!!)
> 

Looking back through the mailing list, there have been
various incarnations of this patch to add MSI support to the
44x.  Every one that I looked at had this same line of code
in it so I am not sure they worked.  In any case I am trying
to make it work on my system (which is how I found the bug).
When I enable the "sdr-base" line in the MSI section of my
dts, it just reboots continuosly right after "Loading Device
Tree ....".  I tried renaming it to "msi-sdr-base" just in
case there was a conflict (since it is reading through the
entire tree) but that did not help.  If I understand
correctly, the ppc4xx_msi_probe function must be executing
very early since I suspect something in setup_pcieh_hw is 
what causes it to fail.  

ayman