Re: [PATCH 2/6] PCI: acpiphp: enable_device(): rescan even if no newdevices on slot

[Yinghai Lu]

On Tue, Jun 25, 2013 at 9:22 AM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
>
> pci_scan_slot() returns number of new devices connected *directly*
> connected to the slot. Current enable_device() checks the return value
> and stops if it doesn't see a new device.
>
> In Thunderbolt chaining case the new device can be deeper in hierarchy, so
> do the rescan anyway.
>
> Because of that we must make sure that pcibios_resource_survey_bus() and
> check_hotplug_bridge() get called only for a just found bus and not the
> ones already added to the system. Failure to do so will lead to resource
> conflicts.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> ---
>  drivers/pci/hotplug/acpiphp_glue.c | 18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index b983e29..80a6ea1 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -685,18 +685,13 @@ static int __ref enable_device(struct acpiphp_slot *slot)
>         struct pci_dev *dev;
>         struct pci_bus *bus = slot->bridge->pci_bus;
>         struct acpiphp_func *func;
> -       int num, max, pass;
> +       int max, pass;
>         LIST_HEAD(add_list);
>
>         list_for_each_entry(func, &slot->funcs, sibling)
>                 acpiphp_bus_add(func);
>
> -       num = pci_scan_slot(bus, PCI_DEVFN(slot->device, 0));
> -       if (num == 0) {
> -               /* Maybe only part of funcs are added. */
> -               dbg("No new device found\n");
> -               goto err_exit;
> -       }
> +       pci_scan_slot(bus, PCI_DEVFN(slot->device, 0));
>
>         max = acpiphp_max_busnr(bus);
>         for (pass = 0; pass < 2; pass++) {
> @@ -707,8 +702,11 @@ static int __ref enable_device(struct acpiphp_slot *slot)
>                             dev->hdr_type == PCI_HEADER_TYPE_CARDBUS) {
>                                 max = pci_scan_bridge(bus, dev, max, pass);
>                                 if (pass && dev->subordinate) {
> -                                       check_hotplug_bridge(slot, dev);
> -                                       pcibios_resource_survey_bus(dev->subordinate);
> +                                       if (!dev->subordinate->is_added) {
> +                                               check_hotplug_bridge(slot, dev);
> +                                               pcibios_resource_survey_bus(
> +                                                       dev->subordinate);
> +                                       }

No,
this change will totally disable calling
check_hotplug_bridge/pcibios_resource_survey_bus()

as pci_scan_bridge/pci_scan_child_bus will set dev->subordinate->is_added...

Please note: recently is_added setting is moved early before
pci_bus_add_devices...

>                                         __pci_bus_size_bridges(dev->subordinate,
>                                                                &add_list);
>                                 }
> @@ -742,8 +740,6 @@ static int __ref enable_device(struct acpiphp_slot *slot)
>                 }
>         }
>
> -
> - err_exit:
>         return 0;
>  }
>
> --
> 1.8.3.1
>
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