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PCI: work around Stratus ftServer broken PCIe hierarchy

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A PCIe downstream port is a P2P bridge.  Its secondary interface is
a link that should lead only to device 0 (unless ARI is enabled)[1], so
we don't probe for non-zero device numbers.

Some Stratus ftServer systems have a PCIe downstream port (02:00.0) that
leads to both an upstream port (03:00.0) and a downstream port (03:01.0),
and 03:01.0 has important devices below it:

  [0000:02]-+-00.0-[03-3c]--+-00.0-[04-09]--...
                            \-01.0-[0a-0d]--+-[USB]
                                            +-[NIC]
                                            +-...

Previously, we didn't enumerate device 03:01.0, so USB and the network
didn't work.  This patch adds a DMI quirk to scan all device numbers,
not just 0, below a downstream port.

Based on a patch by Prarit Bhargava.

[1] PCIe spec r3.0, sec 7.3.1

CC: Myron Stowe <[email protected]>
CC: Don Dutile <[email protected]>
CC: James Paradis <[email protected]>
CC: Matthew Wilcox <[email protected]>
CC: Jesse Barnes <[email protected]>
CC: Prarit Bhargava <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
This commit is contained in:
Bjorn Helgaas 2012-04-30 15:21:02 -06:00
commit 284f5f9dba
5 changed files with 34 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

3
drivers/pci/pci.c
View file

@ -22,6 +22,7 @@
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/pm_runtime.h>
#include <asm-generic/pci-bridge.h>
#include <asm/setup.h>
#include "pci.h"
@ -3893,6 +3894,8 @@ static int __init pci_setup(char *str)
pcie_bus_config = PCIE_BUS_PERFORMANCE;
} else if (!strncmp(str, "pcie_bus_peer2peer", 18)) {
pcie_bus_config = PCIE_BUS_PEER2PEER;
} else if (!strncmp(str, "pcie_scan_all", 13)) {
pci_add_flags(PCI_SCAN_ALL_PCIE_DEVS);
} else {
printk(KERN_ERR "PCI: Unknown option `%s'\n",
str);

8
drivers/pci/probe.c
View file

@ -10,6 +10,7 @@
#include <linux/module.h>
#include <linux/cpumask.h>
#include <linux/pci-aspm.h>
#include <asm-generic/pci-bridge.h>
#include "pci.h"
#define CARDBUS_LATENCY_TIMER 176 /* secondary latency timer */
@ -1395,10 +1396,13 @@ static unsigned no_next_fn(struct pci_dev *dev, unsigned fn)
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 ||
parent->pcie_type == PCI_EXP_TYPE_DOWNSTREAM)
if (parent->pcie_type == PCI_EXP_TYPE_ROOT_PORT)
return 1;
if (parent->pcie_type == PCI_EXP_TYPE_DOWNSTREAM &&
!pci_has_flag(PCI_SCAN_ALL_PCIE_DEVS))
return 1;
return 0;
}