Re: One chart on pci bridge and its bus and their children

[Ram Pai <linuxram@us.ibm.com>]

On Tue, Jun 05, 2012 at 11:26:27AM +0800, Richard Yang wrote:
> 
> All, 
> 
> I draw a chart on the relationship of bridge/bus/devics.
> 
> I am not sure it is exact, so please correct me if it is not correct.

A clearer representation can be found at http://tldp.org/LDP/tlk/dd/pci.html		
in section 6.6.1

> 
> BTW, the pci_bus->self, pci_bus->bridge seem to point the same thing.
> So this is really necessary to do this?

pci_bus->self points to the pci_dev structure, and pci_bus->bridge
points to the device structure. Both correspond to the same bridge. BTW: device
structure is the basic structure to represent any device in the system,
not necessarily pci device.


> 
>                             Bus 0(pci_bus)                      
>                             +--------------------+<----+
>                             |                    |     |
>                             +--------------------+     |
>                                                        |
>                                                        |
>                              Bridge(pci_dev)           |                     
>                             +--------------------+<----|---+--------------+
>                             |subordinate(pci_bus)|-+   |   |              |
>                             +--------------------+ |   |   |              |
>                                                    |   |   |              |
>                                                    |   |   |              |
>                                                    |   |   |              |
>                             Bus 1(pci_bus)         |   |   |              |
>                        +--->+-------------------+<-+   |   |              |
>                        |    |parent(pci_bus)    |------+   |              |
>                        |    +-------------------+          |              |
>                        |    |self(pci_dev)      |----------+              |
>                        |    |bridge(device)     |                         |
>                        |    +-------------------+                         |
>                        |    |devices(list_head) |                         |
>                        |    +--------+----------+                         |
>                        |             |                                    |
>                        |      ----+--+---+----                            |
>    pci_dev             |          |      |          pci_dev               |
>    +---------------+<--|----------+      +--------->+-----------------+   |
>    |bus(pci_bus)   |---+                            |bus(pci_bus)     |   |
>    +---------------+                                +-----------------+   |
>    |dev.parent     |                                |dev.parent       |---+
>    +---------------+                                +-----------------+