Re: [PATCH 24/32] pci: PCIe driver for Marvell Armada 370/XP systems

[Jason Gunthorpe <jgunthorpe@obsidianresearch.com>]

On Thu, Mar 07, 2013 at 09:08:32AM +0100, Thierry Reding wrote:

> Actually I do use device_type = "pciex" for the pci@1,0 and pci@2,0
> nodes which was suggested back when I first posted this series. Yet the
> address translation still works properly. And it should since they are
> translated to the parent bus which is used to access the configuration
> space window for each root port.

Right - pciex != pci - as you note:

> Looking at the code it looks indeed like the OF core only matches on
> "pci" (and "vci"), but not "pciex". Perhaps I should change both nodes
> to device_type = "pci" and see what the results are.

The string 'pci' engages the special behavior, pciex isn't a valid
keyword.

This is why I keep saying these bindings need to use 'device_type = "pci"' :)

> > Both have various problems, but I think I prefer the first one as it
> > doesn't conflate the contoller registers and host apertures in a
> > single ranges..
> 
> I think a better alternative would be (and this matches what Thomas has
> said elsewhere) to use something like the first alternative but move the
> regs property into the pcie@0,X nodes. That would save us from having to
> index a property in the parent. At least from a DT point of view I find
> that to be a more consistent representation.

You are thinking a new property 'host-controller-regs' or the like?

> However that would probably not work out-of-the-box with the current OF
> core because of_address_to_resource() won't know how to find the new
> property. The assigned-addresses alternative seems to be the only one
> that would work on the current OF core and achieve proper address
> translation. But it doesn't seem like a good solution either since it
> repurposes the meaning of the property and therefore isn't any better
> than encoding the same information in the reg property.

Except that reg is specifically not supposed to be handling CPU bus
addresses and assigned-addresses is.

Adding a hidden non-standard BAR to model the hidden non-standard
memory region associated with the bridge is a stretch, but it is not a
very big stretch...

In any event, regs should not be used, and something needs to be
decided!

Regards,
Jason