[PATCH v3 00/10] ARM: tegra: Add PCIe device tree support

Thierry Reding thierry.reding at avionic-design.de
Tue Sep 18 02:33:49 EDT 2012

On Sat, Sep 08, 2012 at 11:51:00AM -0600, Bjorn Helgaas wrote:
> On Fri, Sep 7, 2012 at 6:04 PM, Russell King - ARM Linux
> <linux at arm.linux.org.uk> wrote:
> > On Fri, Sep 07, 2012 at 05:34:35PM -0600, Stephen Warren wrote:
> >> I guess it's a pretty basic premise of the current PCI code that all the
> >> PCI scanning happens well before any device drivers are registered,
> >> which in turn means that device_add() doesn't trigger the device's
> >> probe() until much later, after all the fixups and resource assignments
> >> are done?
> >
> > Are you saying that the PCI layer is again screwed up after all my
> > hard work several years ago to ensure that PCI devices are properly
> > setup _before_ they're made available to the PCI drivers then?  That
> > was around the time I was looking at Cardbus stuff, ensuring that that
> > worked with the same guarantees.
> >
> > Not amused.
> >
> > What is wrong with the "probe devices, apply fixups, setup resources,
> > apply more fixups, publish" process that it's had to be yet again
> > broken?
> It seems that there are some bugs in the PCI layer, no doubt
> introduced after all your hard work.  We'll do our best to fix them.
> The particular issue of pci_fixup_irqs() has been on my list for a
> while, and we talked about it at the recent PCI mini-summit.  It's
> clearly broken that we do this with for_each_pci_dev() once at
> boot-time because that does nothing for hot-added devices.  It's also
> broken that it is called after device_add() because the core shouldn't
> touch the device after it's available to drivers.
> This should get fixed reasonably soon, probably not in v3.6, but
> hopefully in v3.7.  It's not completely trivial because many arches
> have the same problem, and we need to fix all of them.

Has there been any progress on this? I've read the PCI mini summit notes
that you posted a while ago but it doesn't mention the pci_fixup_irqs()
issue. Was there some decision as to how this should be solved? If I
understand correctly this should solve the issue that Stephen has been
seeing with bogus interrupt assignments, so we'll need this to fix PCIe
on Tegra. Is there anything I can do to help move this forward?

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