Re: [PATCH V2 5/5] Microblaze: Modifying microblaze PCI subsytem to support generic Xilinx AXI PCIe Host Bridge IP driver

Bjorn Helgaas
2016-02-03T16:32:13Z

[+cc Ben, pcibios_get_phb_of_node() question]

On Tue, Jan 12, 2016 at 11:06:13PM +0530, Bharat Kumar Gogada wrote:
> This patch does required modifications to microblaze PCI subsystem, to
> work with generic driver (drivers/pci/host/pcie-xilinx.c) on Microblaze
> and Zynq.
>
> Signed-off-by: Bharat Kumar Gogada <bharatku@xilinx.com>
> Signed-off-by: Ravi Kiran Gummaluri <rgummal@xilinx.com>
>...

> resource_size_t pcibios_align_resource(void *data, const struct resource *res,
> resource_size_t size, resource_size_t align)
> {
> - struct pci_dev *dev = data;
> resource_size_t start = res->start;
>
> - if (res->flags & IORESOURCE_IO) {
> - if (skip_isa_ioresource_align(dev))
> - return start;
> - if (start & 0x300)
> - start = (start + 0x3ff) & ~0x3ff;
> - }
> -
> return start;

"return res->start;" is sufficient; no need for a temporary variable.

> }
> EXPORT_SYMBOL(pcibios_align_resource);
>
> +int pcibios_add_device(struct pci_dev *dev)
> +{
> + dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(pcibios_add_device);
> +
> /*
> * Reparent resource children of pr that conflict with res
> * under res, and make res replace those children.
> @@ -1335,9 +1308,21 @@ static void pcibios_setup_phb_resources(struct pci_controller *hose,
>
> struct device_node *pcibios_get_phb_of_node(struct pci_bus *bus)
> {
> - struct pci_controller *hose = bus->sysdata;
> + struct device_node *np;
> +
> + for_each_node_by_type(np, "pci") {
> + const void *prop;
> + unsigned int bus_min;
> +
> + prop = of_get_property(np, "bus-range", NULL);
> + if (!prop)
> + continue;
> + bus_min = be32_to_cpup(prop);
> + if (bus->number == bus_min)
> + return np;
> + }
>
> - return of_node_get(hose->dn);
> + return NULL;

Hmmm. The old microblaze code ("return of_node_get(hose->dn);") is
basically the same as the mips and powerpc versions. The new code is
basically the same as the x86 version.

I like the generic weak version in drivers/pci/of.c because it doesn't
use any arch-specific data, and it looks like if we just set the
struct device.of_node members correctly, everything should Just Work.

But Ben added both the generic and the x86 versions the same day, so
there must be some complication:

98d9f30c820d ("pci/of: Match PCI devices to OF nodes dynamically")
3d5fe5a65af9 ("x86/devicetree: Use generic PCI <-> OF matching")

So I guess my question is, why do we need a microblaze-specific
version at all?

Bjorn