RE: Musings on PCI busses

[Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>]

> 1) Probe the host controller in an of_platform driver.  This has the
> advantage of simplicity.  The probe routine will get automatically
> called when the PCI host controller device tree node is registered
> with the of_platform bus.  The bus parenthood also gets reflected in
> the device model and sysfs.  The disadvantage is that it defers PCI
> bus probing until after the of_platform bus is probed (maybe this is
> okay; maybe this already happens anyway).
> =

> 2) Probe the host controller in an subsys_initcall().  Advantage is
> PCI can be probed earlier in the init path.  Disadvantages (minor) are
> that it will always get called if the driver is enabled, and it needs
> to manually search the device tree for PCI nodes.
> =

> I'm leaning towards making it an of_platform driver.  Doing so also
> makes it available to other powerpc processors (not just virtex) in
> the case where a Xilinx FPGA is welded up to a discrete SoC and a host
> controller instance is put into the FPGA.  (one of those weird things
> people do when they have an FPGA in their system).

I agree that something is called for...  The first might be slightly
simpler, since it would probably transparently deal with the presence
of more than one PLB->PCI bridge?

Steve


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