Integrator PCI base dilemma

[Russell King - ARM Linux]

On Fri, Mar 22, 2013 at 12:33:20PM -0600, Jason Gunthorpe wrote:
> On Fri, Mar 22, 2013 at 12:34:59PM +0000, Arnd Bergmann wrote:
> 
> > > So that leaves cns3xxx, tegra and ks8695 being the non-plat ones which
> > > are "different" from the majority on ARM.
> > 
> > Well, those and all the ones that chose to set up their windows in the
> > same way like the plat-orion based ones.
> 
> The orion stuff can create a second mapping into PCI address space
> that can remap and generate VGA compatible bus addresses. That
> techinque would duplicate how x86 handles this stuff these days.
> 
> Things are more complex on PCI-E. There is no subtractive decode in
> PCI-E so you either need the magic window like x86 uses, or the bridge
> windows and apertures have to be set 'just so'.

That is no different to platforms like the footbridge.  We have to
place system memory above the VGA window to ensure that everything
works as it should.