Re: [PATCH] PCI: fix sriov enabling with virtual bus

[Yinghai Lu <yinghai@kernel.org>]

On Wed, Nov 5, 2014 at 1:57 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
>
> It's relatively common to start with a pci_dev and look for an ACPI handle
> that corresponds to that device or the closest enclosing scope, so maybe
> there should be a way to do that directly.
>
> For pci_get_hp_params(), I think the current code is actually slightly
> buggy because we don't look for _HPP/_HPX on the device itself; we only
> look at the bridges upstream from it.
>
> What I had in mind was something like the following (untested and not for
> application).



> + * Search for an ACPI handle.  The PCI device itself may have one, or an
> + * upstream device (either a PCI-to-PCI bridge or a PCI host bridge) may
> + * have one.
> + */
> +acpi_handle pci_find_acpi_handle(struct pci_dev *pdev)
> +{
> +       struct device *dev;
> +       acpi_handle handle;
> +       struct pci_bus *bus;
> +
> +       dev = &pdev->dev;
> +       handle = ACPI_HANDLE(dev);
> +       while (!handle) {
> +               pdev = pci_physfn(pdev);

I'm a little worried about to apply hpx value for PFs to VFs.

> +               bus = pdev->bus;
> +               if (pci_is_root_bus(bus))
> +                       dev = bus->bridge;
> +               else {
> +                       pdev = bus->self;
> +                       dev = &pdev->dev;
> +               }
> +               handle = ACPI_HANDLE(dev);
> +       }
> +       return handle;
> +}


Also found another problem,
pci_device_add==>pci_configure_device==>program_hpp_type2() path.
and program_hpp_type2() will check dev->subordinate().

but at the time child bridge is not scanned yet.

Maybe we should move pci_configure_device later ?

Yinghai Lu