* Han, Weidong <weidong.han@xxxxxxxxx> wrote:
> Ingo Molnar wrote:
> > * Han, Weidong <weidong.han@xxxxxxxxx> wrote:
> >
> >> Siddha, Suresh B wrote:
> >>> On Wed, 2009-05-06 at 23:16 -0700, Han, Weidong wrote:
> >>>> @@ -634,6 +694,44 @@ static int ir_parse_ioapic_scope(struct
> >>>> acpi_dmar_header *header, " 0x%Lx\n",
> >>>> scope->enumeration_id, drhd->address);
> >>>>
> >>>> + bus = pci_find_bus(drhd->segment, scope->bus);
> >>>> + path = (struct acpi_dmar_pci_path *)(scope + 1); + count =
> >>>> (scope->length - + sizeof(struct acpi_dmar_device_scope))
> >>>> + / sizeof(struct acpi_dmar_pci_path);
> >>>> +
> >>>> + while (count) {
> >>>> + if (pdev)
> >>>> + pci_dev_put(pdev);
> >>>> +
> >>>> + if (!bus)
> >>>> + break;
> >>>> +
> >>>> + pdev = pci_get_slot(bus,
> >>>> + PCI_DEVFN(path->dev, path->fn));
> >>>> + if (!pdev)
> >>>> + break;
> >>>
> >>> ir_parse_ioapic_scope() happens very early in the boot. So, I
> >>> don't think we can do the pci related discovery here.
> >>>
> >>
> >> Thanks for your pointing it out. It should enable the source-id
> >> checking for io-apic's after the pci subsystem is up. I will
> >> change it.
> >
> > Note, there's ways to do early PCI quirks too, check
> > arch/x86/kernel/early-quirks.c. It's done by reading the PCI
> > configuration space directly via a careful early-capable subset of
> > the PCI config space APIs.
> >
> > But it's a method of last resort.
> >
>
> Thanks for your reminder. It can use direct PCI access here as follows. It's easy and clean. I think it's better than adding the source-id checking for io-apic's after the pci subsystem is up. I will send out updated patches after some tests.
>
> @@ -634,6 +695,24 @@ static int ir_parse_ioapic_scope(struct acpi_dmar_header *header,
> " 0x%Lx\n", scope->enumeration_id,
> drhd->address);
>
> + bus = scope->bus;
> + path = (struct acpi_dmar_pci_path *)(scope + 1);
> + count = (scope->length -
> + sizeof(struct acpi_dmar_device_scope))
> + / sizeof(struct acpi_dmar_pci_path);
> +
> + while (--count > 0) {
> + /* Access PCI directly due to the PCI
> + * subsystem isn't initialized yet.
> + */
> + bus = read_pci_config_byte(bus, path->dev,
> + path->fn, PCI_SECONDARY_BUS);
> + path++;
> + }
> +
> + ir_ioapic[ir_ioapic_num].bus = bus;
> + ir_ioapic[ir_ioapic_num].devfn =
> + PCI_DEVFN(path->dev, path->fn);
looks good IMO, beyond the obligatory comment-style nitpick [*] :-)
Also, the function above seems to be way too large - please split it
into a couple of natural helper functions.
Thanks,
Ingo
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