tree ea6775f09df6d463d4f7f3047246701a9f644bb2
parent 72e0ef0e5f067fd991f702f0b2635d911d0cf208
author Ivan Kokshaysky <ink@jurassic.park.msu.ru> 1584215035 +0000
committer Bjorn Helgaas <bhelgaas@google.com> 1585579954 -0500

PCI: Add support for root bus sizing

In certain cases we should be able to enumerate IO and MEM ranges of all
PCI devices installed in the system, and then set respective host bridge
apertures basing on calculated size and alignment.  Particularly when
firmware is broken and fails to assign bridge windows properly, like on
Alpha UP1500 platform.

Actually, almost everything is already in place, and required changes are
minimal:

- add "size_windows" flag to struct pci_host_bridge: when set, it
  instructs __pci_bus_size_bridges() to continue with the root bus;
- in the __pci_bus_size_bridges() path: add checks for bus->self,
  as it can legitimately be null for the root bus.

Link: https://lore.kernel.org/r/20200314194355.GA12510@mail.rc.ru
Tested-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>