On Wed, Jun 24, 2015 at 08:34:28AM +1000, Benjamin Herrenschmidt wrote:

On Mon, 2014-09-29 at 12:17 -0600, Bjorn Helgaas wrote:

quoted

This seems like more than necessary, but I don't know all the history.
In particular, I don't know why PCI_PROBE_ONLY should make a
difference to things like claiming resources.

It shouldn't ... we created that option on ppc originally to avoid
allocation/reallocation of resources. If they are bad, leave them bad,
but it was never a question of disabling all these other things.

(Ok, the MRSS/MPS is debatable, but why not plumb the parent pointers
and why not claim ? That doesn't make sense to me).

You could look back over the history of arch/arm/kernel/bios32.c and
see that it was introduced by Will Deacon when he stripped out the
ARM version in favour of the generic version, and was found to be
necessary then.

I think the question has to be asked (based upon what Ben's saying)
and what's identified in these commits as a failure case
(pci_enable_resource failing when PCI_PROBE_ONLY is enabled) -
why is the PCI core creating per-device resources which do not have
parents.

I've no idea on that; the only ARM boxes I have use the kernel's PCI
allocation, I don't have these boxes which want to use PCI_PROBE_ONLY
so it's something I have zero knowledge of.

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