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

Bjorn Helgaas
2016-02-03T16:38:05Z

[+cc Ben for real this time]

On Wed, Feb 03, 2016 at 10:32:07AM -0600, Bjorn Helgaas wrote:
> [+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
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