[PATCH] pci: Workaround Stratus broken PCIE hierarchy

[Prarit Bhargava <prarit@redhat.com>]

Stratus systems have a hierarchy that includes a PCIE Downstream bridge
connected to a PCIE Upstream bridge and a PCI Downstream bridge.  The system
boots with this wrong hierarchy into a crippled mode (USB doesn't work,
network doesn't work ...).  Avoiding the Downstream bridge check in
only_one_child() causes all the bridges to be enumerated and the system
to function properly.

Unfortunately this hardware is currently available so we should at least
keep it functional.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>

Cc: mstowe@redhat.com
Cc: ddutile@redhat.com
Cc: jparadis@redhat.com
Cc: matthew.wilcox@linux.intel.com
Cc: jbarnes@virtuousgeek.org
---
 drivers/pci/probe.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 04e74f4..bc76812 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -10,6 +10,7 @@
 #include <linux/module.h>
 #include <linux/cpumask.h>
 #include <linux/pci-aspm.h>
+#include <linux/dmi.h>
 #include "pci.h"
 
 #define CARDBUS_LATENCY_TIMER	176	/* secondary latency timer */
@@ -1275,7 +1276,15 @@ static int only_one_child(struct pci_bus *bus)
 	struct pci_dev *parent = bus->self;
 	if (!parent || !pci_is_pcie(parent))
 		return 0;
-	if (parent->pcie_type == PCI_EXP_TYPE_ROOT_PORT ||
+	if (parent->pcie_type == PCI_EXP_TYPE_ROOT_PORT)
+		return 1;
+	/*
+	 * Stratus/NEC ftServer systems have a broken PCIE hierarchy in which
+	 * one upstream and one downstream port are plugged into a downstream
+	 * port.  Avoiding the downstream port check here results in a
+	 * functional system.
+	 */
+	if (!dmi_name_in_vendors("ftServer") &&
 	    parent->pcie_type == PCI_EXP_TYPE_DOWNSTREAM)
 		return 1;
 	return 0;
-- 
1.7.1