On Fri, Feb 10, 2012 at 8:55 AM, Bjorn Helgaas [off-list ref] wrote:
...

quoted

I mean, we can unify sysdata usuage, make them all most the same.

and for some sysdata, already acting like host_bridge struct with
domain, numa_node, and resources.

quoted

If you can show an example of what you mean, maybe it will help me understand.

just looked the sys_data of different arch,

looks like pci_sys_data for arm already include the io offset

arch/arm/include/asm/mach/pci.h::

struct pci_sys_data {
#ifdef CONFIG_PCI_DOMAINS
       int             domain;
#endif
       struct list_head node;
       int             busnr;          /* primary bus number
        */
       u64             mem_offset;     /* bus->cpu memory mapping
offset       */
       unsigned long   io_offset;      /* bus->cpu IO mapping offset
        */
       struct pci_bus  *bus;           /* PCI bus
        */
       struct list_head resources;     /* root bus resources (apertures)

Let me try again.  Maybe your idea is that we should create something
like "struct pcibios_sysdata" and require every arch to define a
struct with that name.  Every arch's struct would contain some members
such as "domain," "mem_offset," "io_offset," and "resources."  These
would have standard names & types across all arches and would be
referenced by the PCI core.  In addition, the struct could include
arch-specific data such as "acpi_handle," "iommu," etc.

That way, the core could implement things like pci_domain_nr() and
pci_bus_to_resource() by using the data in struct pcibios_sysdata.
The current "void *sysdata" parameters to pci_scan_bus() and friends
would become "struct pcibios_sysdata *sysdata".

I like the idea of unifying the sysdata struct name and changing from
a "void *" to something like "struct pcibios_sysdata *".  That might
be worth doing.

what i am mean:
1. make every arch to use same name for the struct, but could have
different contents.
   struct pci_sys_data.
2. unify member field name, by changing name
    pci_first_busno ==> first_busno
    pci_last_busno ==> last_busno
    or adding
    first_busno
    last_busno
3. changing more filed like domain, node
    and io_offset, mem_offset
...

Yinghai