Greg KH
2005-07-01T20:57:49Z

[PATCH] PCI: handle subtractive decode pci-pci bridge better

With the number of PCI bus resources increased to 8, we can
handle the subtractive decode PCI-PCI bridge like a normal
bridge, taking into account standard PCI-PCI bridge windows
(resources 0-2). This helps to avoid problems with peer-to-peer DMA
behind such bridges, poor performance for MMIO ranges outside bridge
windows and prefetchable vs. non-prefetchable memory issues.

To reflect the fact that such bridges do forward all addresses to
the secondary bus (transparency), remaining bus resources 3-7 are
linked to resources 0-4 of the primary bus. These resources will be
used as fallback by resource management code if allocation from
standard bridge windows fails for some reason.

Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Acked-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
commit 90b54929b626c80056262d9d99b3f48522e404d0
tree d5cb91ff7bd0ac9ffeab5f7bf68235e8b35d050c
parent a03fa955576af50df80bec9127b46ef57e0877c0
author Ivan Kokshaysky <ink@jurassic.park.msu.ru> Tue, 07 Jun 2005 04:07:02 +0400
committer Greg Kroah-Hartman <gregkh@suse.de> Fri, 01 Jul 2005 13:35:50 -0700

drivers/pci/probe.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -239,9 +239,8 @@ void __devinit pci_read_bridge_bases(str

if (dev->transparent) {
printk(KERN_INFO "PCI: Transparent bridge - %s\n", pci_name(dev));
- for(i = 0; i < PCI_BUS_NUM_RESOURCES; i++)
- child->resource[i] = child->parent->resource[i];
- return;
+ for(i = 3; i < PCI_BUS_NUM_RESOURCES; i++)
+ child->resource[i] = child->parent->resource[i - 3];
}

for(i=0; i<3; i++)