On Wed, Jul 3, 2013 at 8:04 AM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> In hotplug case (especially with Thunderbolt enabled systems) we might need
> to call pcibios_resource_survey_bus() several times for a bus. The function
> ends up calling pci_claim_resource() for each bridge resource that then
> fails claiming that the resource exists already (which it does). Once this
> happens the resource is invalidated thus preventing devices behind the
> bridge to allocate their resources.
>
> To fix this we do what has been done in pcibios_allocate_dev_resources()
> and check 'parent' of the given resource. If it is non-NULL it means that
> the resource has been allocated already and we can skip it. We do the same
> for ROM resources as well.
>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
This looks reasonable to me.
However, the use of "r->parent" to determine whether the resource is
already allocated is nothing specific to x86. So I think we might be
missing an opportunity to make this more consistent across
architectures. I looked at other callers of pci_claim_resource() for
bridge and ROM resources, and it looks like we might be able to make
similar changes in:
frv pcibios_allocate_bus_resources()
ia64 pcibios_fixup_resources() (via pcibios_fixup_bridge_resources())
mn10300 pcibios_allocate_bus_resources()
mn10300 pcibios_assign_resources() (ROM)
mn10300 pcibios_fixup_device_resources()
parisc lba_fixup_bus()
I really hate the idea of fixing something for x86 but not for other
arches, so maybe somebody could take a deeper look at this and see if
it would make sense to change the other arches, too.
Bjorn
> ---
> arch/x86/pci/i386.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
> index 94919e3..db6b1ab 100644
> --- a/arch/x86/pci/i386.c
> +++ b/arch/x86/pci/i386.c
> @@ -210,6 +210,8 @@ static void pcibios_allocate_bridge_resources(struct pci_dev *dev)
> r = &dev->resource[idx];
> if (!r->flags)
> continue;
> + if (r->parent) /* Already allocated */
> + continue;
> if (!r->start || pci_claim_resource(dev, idx) < 0) {
> /*
> * Something is wrong with the region.
> @@ -318,6 +320,8 @@ static void pcibios_allocate_dev_rom_resource(struct pci_dev *dev)
> r = &dev->resource[PCI_ROM_RESOURCE];
> if (!r->flags || !r->start)
> return;
> + if (r->parent) /* Already allocated */
> + return;
>
> if (pci_claim_resource(dev, PCI_ROM_RESOURCE) < 0) {
> r->end -= r->start;
> --
> 1.8.3.2
>
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