[PATCH 11/11] RFC: ARM: get PCI device IRQs from device tree

[Linus Walleij]

On Thu, Apr 4, 2013 at 5:01 PM, Linus Walleij <linus.walleij at linaro.org> wrote:

> This currently bugs out - when trying to get the IRQs for
> devices of_irq_map_pci() reads the IRQ pin from the PCI config
> space successfully, then comes to trying to look up the parent
> PCI device by checking pdev->bus->self, which is NULL, then
> tries to treat it as a bridge doing pci_bus_to_OF_node(pdev->bus)
> which also results in NULL and it bails out.
>
> No clue why this is so - some problem with the parent of this
> bus not being a PCI device in itself? Help.

Tracked this down to a point where in drivers/pci/of.c
pci_set_bus_of_node() is called on the root bus, at which
point it calls pcibios_get_phb_of_node() which has no clue
on how to obtain the DT node for the root hub. (Only bridges.)

Inserting this naïve fragment into the PCI driver makes things
tick:

+struct device_node *static_root;
+
+struct device_node *pcibios_get_phb_of_node(struct pci_bus *bus)
+{
+       return static_root;
+}
+

In probe():
+       static_root = np;

It'll override the weak symbol and make things work.

I guess this is something for kernel/bios32.c to implement
if we want to support DT on these PCI adapters, so looking
into that next...

But how do others get their things to work? Not using bios32?
I wonder...

Yours,
Linus Walleij