tree e1554b1c3bc793c204c9285e1f7455a7d41ee906
parent 7f5dac3eb6c7d2646d0de28f5187a6f039391d35
author Yinghai Lu <yinghai@kernel.org> 1325916214 -0800
committer Yinghai Lu <yinghai@kernel.org> 1325916214 -0800

PCI: Fixing multiple retrying with pci resource optional resources allocation under multi bridges

One system has devices that support sriov and those devices
are connected to pcie switch to pcie root port.

 +-[0000:80]-+-00.0-[81-8f]--
 |           +-01.0-[90-9f]--
 |           +-02.0-[a0-af]----00.0-[a1-a3]--+-02.0-[a2]--+-00.0 Oracle Corporation Device 207a
 |           |                               \-03.0-[a3]--+-00.0 Oracle Corporation Device 207a
 |           +-02.2-[b0-bf]----00.0-[b1-b3]--+-02.0-[b2]--+-00.0 Oracle Corporation Device 207a
 |           |                               \-03.0-[b3]--+-00.0 Oracle Corporation Device 207a

When BIOS does not assign resource for sriov bar, kernel pci reallocation
ony go up to one bridge and then failed to get resource to all sriov bar.
even We have big enough range in peer root bus for allocation.
Specifically, only bridge a1:02.0 level get cleared, and reallocated. kernel does not
go up to clear bridge 80:02.0 level.

To make it go upper levels, during retring, We need to treat good to have
as must have.

Only last try will treat good to have as optional, at that time, parent
bridges resource already released so it will have chance to get assigned
with must_have plus good_to_have for all children devices.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>