Re: [PATCH -v11 04/30] PCI: Add busn_res into struct pci_bus.
From: Yinghai Lu
Date: Mon Apr 30 2012 - 20:32:18 EST
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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