PCI: clear bridge resource range if BIOS assigned bad one

Yannick found that video does not work with 2.6.34.  The cause of this
bug was that the BIOS had assigned the wrong range to the PCI bridge
above the video device.  Before 2.6.34 the kernel would have shrunk
the size of the bridge window, but since
  d65245c PCI: don't shrink bridge resources
the kernel will avoid shrinking BIOS ranges.

So zero out the old range if we fail to claim it at boot time; this will
cause us to allocate a new range at startup, restoring the 2.6.34
behavior.

Fixes regression https://bugzilla.kernel.org/show_bug.cgi?id=16009.

Reported-by: Yannick <yannick.roehlly@free.fr>
Acked-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index 97da2ba9344b..6fdb3ec30c31 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -96,6 +96,7 @@ EXPORT_SYMBOL(pcibios_align_resource);
  *        the fact the PCI specs explicitly allow address decoders to be
  *        shared between expansion ROMs and other resource regions, it's
  *        at least dangerous)
+ *      - bad resource sizes or overlaps with other regions
  *
  *  Our solution:
  *      (1) Allocate resources for all buses behind PCI-to-PCI bridges.
@@ -136,6 +137,7 @@ static void __init pcibios_allocate_bus_resources(struct list_head *bus_list)
                                          * child resource allocations in this
                                          * range.
                                          */
+                                        r->start = r->end = 0;
                                         r->flags = 0;
                                 }
                         }