Re: PCIe device tree support

[Bjorn Helgaas <bhelgaas@xxxxxxxxxx>]

On Wed, Feb 22, 2012 at 12:24 AM, Thierry Reding
<thierry.reding@xxxxxxxxxxxxxxxxx> wrote:
> [Adding Jesse Barnes and the linux-pci mailing list to CC.]
>
> * Stephen Warren wrote:
>> Thierry Reding wrote at Monday, February 20, 2012 12:18 PM:
>> > I would like to add device tree support for the Tegra2 PCIe controller. From
>> > what I understand this will require the PCIe code to be rewritten as a proper
>> > platform driver in order to be able to instantiate it via the device tree. Is
>> > that correct?
>>
>> That's probably the cleanest way, yes.
>>
>> Is there a drivers/ directory for PCI/PCIe host controllers? Moving the
>> code there might be nice if so, although IIRC when I asked Olof about
>> that a number of months back, he said quite a few host controllers were
>> in arch/...
>
> Most PCI/PCIe host controller drivers seem to currently be in arch/. Is there
> a specific reason for this? Would it be acceptable to put any new drivers
> below drivers/pci/?

PCI host bridges aren't architected, so discovering them and their
properties has historically been mostly architecture-specific.  ACPI
is one exception (with a driver in drivers/acpi/pci_root.c) and it
sounds like device tree might be a similar exception.  If you can make
a non-arch-specific driver and put it somewhere other than arch/, I'm
all in favor of that, especially if you can make it usable by other
arches that use device tree.  Where to put it?  I dunno.  drivers/pci/
sounds like a reasonable possibility.

Bjorn
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