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    SubjectRe: One problem in reassign pci bus number?
    From
    On Sun, May 13, 2012 at 6:55 PM, Richard Yang
    <weiyang@linux.vnet.ibm.com> wrote:
    > On Mon, Apr 23, 2012 at 03:46:03PM -0400, Don Dutile wrote:
    >>On 04/22/2012 11:52 AM, Richard Yang wrote:
    >>>All,
    >>>
    >>>I am reading the pci_scan_bridge() and not sure what will happen in
    >>>following situation.
    >>>
    >>>Suppose the kernel is not passed the pci=assign-busses.
    >>>
    >>>Below is a picture about the pci system.
    >>>
    >>>                    +-------+
    >>>                    |       | root bridge(0,255)
    >>>                    +---+---+
    >>>                        |          Bus 0
    >>>       -----+-----------+------------------------------+--
    >>>            |                                          |
    >>>            |                                          |
    >>>            |                                          |
    >>>       +----+----+                               +-----+-----+
    >>>       |         |  B1(1,15)                     |           |B2(16,28)
    >>>       +----+----+                               +-----+-----+
    >>>            |  Bus 1                                   |    Bus 16
    >>>       -----+-----------------------         ----------+----------------
    >>>                             |
    >>>                        +----+----+
    >>>                        |         | B3
    >>>                        +---------+
    >>>
    >>>Suppose B1 and B2 works fine with the BIOS, which get the right bus
    >>>number and range.
    >>>
    >>>B3 does not works fine with the BIOS, which doesn't get the bus number.
    >>>
    >>>So in pci_scan_bridge(), B3 will be met in the second pass and get bus
    >>>number 16?
    >>
    > Yinghai,
    >
    > Take my original question.
    >
    > B3 doesn't get the bus number, which its parent doesn't have free bus
    > number and there is no gap between B1 and B2.
    >
    > So in this case, the probe_resource() can't find bus number for B3.
    > Then cause pci_bridge_probe_busn_res() return non-zero.
    >
    > Then B3 couldn't work fine?

    B3 is on Bus 1? B3 is the one of bridges on Bus1?

    if B3 is only bridge on Bus1, it probe_resource should return [2,15]
    at first, and then scan B3.

    Yinghai
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