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SubjectRe: [PATCH 2/2] PCI, ACPI, x86: update MMCFG information when hot-plugging PCI host bridges
Your patch looks good to me.

I have some comments.

(2012/04/09 2:12), Jiang Liu wrote:
> This patch enhances pci_root driver to update MMCFG information when
> hot-plugging PCI root bridges on x86 platforms.
>

Do you have the patch that can be applied to Bjorn's pci tree?

<snip.>

> +int arch_acpi_pci_root_add(struct acpi_pci_root *root)
> +{
> + int result = 0;
> + acpi_status status;
> + unsigned long long base_addr;
> + struct pci_mmcfg_region *cfg;
> +
> + /*
> + * Try to insert MMCFG information for host bridges with _CBA method
> + */
> + status = acpi_evaluate_integer(root->device->handle, METHOD_NAME__CBA,
> + NULL,&base_addr);
> + if (ACPI_SUCCESS(status)) {
> + result = pci_mmconfig_insert(root->segment,
> + root->secondary.start,
> + root->secondary.end,
> + base_addr);
> + /*
> + * MMCFG information for hot-pluggable host bridges may have
> + * already been added by __pci_mmcfg_init();
> + */
> + if (result == -EEXIST)
> + result = 0;

Just for confirmation.
From my interpretation of PCI firmware spec, MCFG doesn't have any entry
for hot-pluggable hostbridge. So I assume this is for the machine that
is not compliant to the spec. Is my understanding same as yours?

<snip.>

> static int __devinit acpi_pci_root_add(struct acpi_device *device)
> {
> unsigned long long segment, bus;
> @@ -504,6 +514,14 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
> strcpy(acpi_device_class(device), ACPI_PCI_ROOT_CLASS);
> device->driver_data = root;
>
> + if (arch_acpi_pci_root_add(root)) {
> + printk(KERN_ERR PREFIX
> + "can't add MMCFG information for Bus %04x:%02x\n",
> + root->segment, (unsigned int)root->secondary.start);
> + result = -ENODEV;
> + goto out_free;
> + }

Desn't this break the system that doesn't support MMCONFIG?

In my understanding, arch_acpi_pci_root_add() returns -ENODEV if
mmconfig information is found neither in MCFG table nor _CBA. And
pci root bridge initialization seems to fail arch_acpi_pci_root_add()
returns non-zero value.

Regards,
Kenji Kaneshige


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