Re: [PATCH] ACPI: Unneccessary to scan the PCI bus already scanned.

Zhao Yakui
2008-03-03T08:30:42Z

On Mon, 2008-03-03 at 08:32 +0100, Ingo Molnar wrote:
> small typo:
>
> > + * If the desired bus exits, the content of bus->sysdata will
> ^--- exists
> > + * be replaced by sd.
>
> also, it's not clear to me why the patch helps. Why does "double
> scanning" cause problems? We register devices twice? Shouldnt that just
> work? (except for a few "device already exists" type of messages)
>
If the desired pci bus(domain,busnum) is already scanned, the call to
pci_scan_bus_parented will return NULL pointer. The function of
pci_bios_acpi_scan_root will also return NULL pointer subsequently. In
such case it will bring that acpi_pci_root driver can't be loaded.

When the system works in acpi mode, there will be some potential problem
if acpi_pci_root driver can't be loaded. For example:
http://bugzilla.kernel.org/show_bug.cgi?id=10124

Thanks.
Yakui

> Ingo