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Message-ID: <4A38B3B4.1020304@jp.fujitsu.com>
Date: Wed, 17 Jun 2009 18:13:24 +0900
From: Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
To: Andrew Patterson <andrew.patterson@...com>
CC: linux-pci@...r.kernel.org, torvalds@...ux-foundation.org,
linux-kernel@...r.kernel.org, jbarnes@...tuousgeek.org
Subject: Re: [PATCH 0/1] Recurse when searching for empty slots in resources
trees
Andrew Patterson wrote:
> I recently ran into a resource collision problem where PCI hot-plug
> operations are failing for certain PCI topologies. One case
> illustrating the problem is using a QLogic PCIe HBA in a slot with a
> PCIe root port as its parent bus. Here is an abbreviated lspci output
> for this topology:
>
> -+-[0000:c2]---00.0-[0000:c3-fb]--+-00.0 QLogic Corp. 8Gb Fibre Channel HBA
> | \-00.1 QLogic Corp. 8Gb Fibre Channel HBA
>
>
>
> c2:00.0 PCI bridge: PCIe Root Port (prog-if 00 [Normal decode])
> Bus: primary=c2, secondary=c3, subordinate=fb, sec-latency=0
> I/O behind bridge: 00001000-0000ffff
> Memory behind bridge: f0000000-fdffffff
> Prefetchable memory behind bridge: 0000080780000000-00000807ffffffff
>
> c3:00.0 Fibre Channel: QLogic Corp. 8Gb Fibre Channel HBA
> Region 0: I/O ports at 8001100 [size=256]
> Region 1: Memory at f0284000 (64-bit, non-prefetchable) [size=16K]
> Region 3: Memory at f0100000 (64-bit, non-prefetchable) [size=1M]
> Expansion ROM at f0240000 [disabled] [size=256K]
>
> c3:00.1 Fibre Channel: QLogic Corp. 8Gb Fibre Channel HBA
> Region 0: I/O ports at 8001000 [size=256]
> Region 1: Memory at f0280000 (64-bit, non-prefetchable) [size=16K]
> Region 3: Memory at f0000000 (64-bit, non-prefetchable) [size=1M]
> Expansion ROM at f0200000 [disabled] [size=256K]
>
> After boot, the resource tree looks like:
>
> f0000000-fdffffff : PCI Bus 0000:c3
> f0000000-fdffffff : PCI Bus 0000:c2
> f0000000-f00fffff : 0000:c3:00.1
> f0000000-f00fffff : qla2xxx
> f0100000-f01fffff : 0000:c3:00.0
> f0100000-f01fffff : qla2xxx
> f0200000-f023ffff : 0000:c3:00.1
> f0240000-f027ffff : 0000:c3:00.0
> f0280000-f0283fff : 0000:c3:00.1
> f0280000-f0283fff : qla2xxx
> f0284000-f0287fff : 0000:c3:00.0
> f0284000-f0287fff : qla2xxx
>
> Note that PCI Bus 0000:c2 is a child of PCI Bus 0000:c3 and has an
> identical address range.
According to the lspci output, PCI Bus 0000:c2 is a parent of PCI
Bus 0000:c3. But they are upside down in resource tree. I guess
this is the root cause of the problem.
I think the reason why it happen is ia64 (I believe you are using
ia64 environment) uses pci_claim_resource(), which calls
insert_resource(), to insert resources. In my understanding, if
two resources having an identical address range are inserted using
insert_resource(), the latter one becomes parent of the first one.
I made a sample patch, though I don't know if it fixes the problem.
I hope this would help you. But please note that it is NOT well
tested.
Thanks,
Kenji Kaneshige
arch/ia64/pci/pci.c | 32 +++++++++++++++++++++++---------
1 file changed, 23 insertions(+), 9 deletions(-)
Index: 20090612/arch/ia64/pci/pci.c
===================================================================
--- 20090612.orig/arch/ia64/pci/pci.c
+++ 20090612/arch/ia64/pci/pci.c
@@ -301,9 +301,10 @@ static __devinit acpi_status add_window(
}
static void __devinit
-pcibios_setup_root_windows(struct pci_bus *bus, struct pci_controller *ctrl)
+pcibios_setup_root_windows(struct pci_bus *bus)
{
int i, j;
+ struct pci_controller *ctrl = bus->sysdata;
j = 0;
for (i = 0; i < ctrl->windows; i++) {
@@ -371,9 +372,6 @@ pci_acpi_scan_root(struct acpi_device *d
* such quirk. So we just ignore the case now.
*/
pbus = pci_scan_bus_parented(NULL, bus, &pci_root_ops, controller);
- if (pbus)
- pcibios_setup_root_windows(pbus, controller);
-
return pbus;
out3:
@@ -456,15 +454,29 @@ pcibios_fixup_resources(struct pci_dev *
{
struct pci_bus_region region;
int i;
+ struct resource *devr, *busr;
for (i = start; i < limit; i++) {
- if (!dev->resource[i].flags)
+ char *dtype = i < PCI_BRIDGE_RESOURCES ? "device" : "bridge";
+
+ devr = &dev->resource[i];
+ if (!devr->flags)
continue;
+
region.start = dev->resource[i].start;
region.end = dev->resource[i].end;
- pcibios_bus_to_resource(dev, &dev->resource[i], ®ion);
- if ((is_valid_resource(dev, i)))
- pci_claim_resource(dev, i);
+ pcibios_bus_to_resource(dev, devr, ®ion);
+ if (!is_valid_resource(dev, i))
+ continue;
+
+ busr = pci_find_parent_resource(dev, devr);
+ if (!busr || request_resource(busr, devr)) {
+ dev_err(&dev->dev, "BAR %d: %s of %s %pR\n", i,
+ busr ? "address space collision on" :
+ "no parent found for",
+ dtype, devr);
+ devr->flags = 0;
+ }
}
}
@@ -487,7 +499,9 @@ pcibios_fixup_bus (struct pci_bus *b)
{
struct pci_dev *dev;
- if (b->self) {
+ if (pci_is_root_bus(b))
+ pcibios_setup_root_windows(b);
+ else {
pci_read_bridge_bases(b);
pcibios_fixup_bridge_resources(b->self);
}
--
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