Re: [PATCH -v11 04/30] PCI: Add busn_res into struct pci_bus.

[Yinghai Lu <yinghai@xxxxxxxxxx>]

On Mon, Apr 30, 2012 at 4:25 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -419,6 +419,7 @@ struct pci_bus {
>>        struct list_head slots;         /* list of slots on this bus */
>>        struct resource *resource[PCI_BRIDGE_RESOURCE_NUM];
>>        struct list_head resources;     /* address space routed to this bus */
>> +       struct resource busn_res;       /* track registered bus num range */
>>
>>        struct pci_ops  *ops;           /* configuration access functions */
>>        void            *sysdata;       /* hook for sys-specific extension */
>
> struct pci_bus already includes "secondary" and "subordinate".    This
> new "busn_res" looks like it will contain the same information.  Why
> do we need both?

In some case the could be different.
for root bus from _CRS, busn_res could bigger than subordinate,
because scan_childbus will update subordinate.

and also we have one resource to insert it into the resource tree, so
later could probe/allocate bus num range.

Yinghai
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