diff options
| author | Bjorn Helgaas <bhelgaas@google.com> | 2017-01-11 09:11:53 -0600 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2017-03-06 17:29:21 -0500 |
| commit | ee21da306c86736bfad4ac4e1d5bfb31f939c9d2 (patch) | |
| tree | 6b43434e812ac4780c31414136451c107544f541 | |
| parent | 61a16adba72382693b1aca33df6b68cf12d7f5ac (diff) | |
PCI: Enumerate switches below PCI-to-PCIe bridges
[ Upstream commit 51ebfc92b72b4f7dac1ab45683bf56741e454b8c ]
A PCI-to-PCIe bridge (a "reverse bridge") has a PCI or PCI-X primary
interface and a PCI Express secondary interface. The PCIe interface is a
Downstream Port that originates a Link. See the "PCI Express to PCI/PCI-X
Bridge Specification", rev 1.0, sections 1.2 and A.6.
The bug report below involves a PCI-to-PCIe bridge and a PCIe switch below
the bridge:
00:1e.0 Intel 82801 PCI Bridge to [bus 01-0a]
01:00.0 Pericom PI7C9X111SL PCIe-to-PCI Reversible Bridge to [bus 02-0a]
02:00.0 Pericom Device 8608 [PCIe Upstream Port] to [bus 03-0a]
03:01.0 Pericom Device 8608 [PCIe Downstream Port] to [bus 0a]
01:00.0 is configured as a PCI-to-PCIe bridge (despite the name printed by
lspci). As we traverse a PCIe hierarchy, device connections alternate
between PCIe Links and internal Switch logic. Previously we did not
recognize that 01:00.0 had a secondary link, so we thought the 02:00.0
Upstream Port *did* have a secondary link. In fact, it's the other way
around: 01:00.0 has a secondary link, and 02:00.0 has internal Switch logic
on its secondary side.
When we thought 02:00.0 had a secondary link, the pci_scan_slot() ->
only_one_child() path assumed 02:00.0 could have only one child, so 03:00.0
was the only possible downstream device. But 03:00.0 doesn't exist, so we
didn't look for any other devices on bus 03.
Booting with "pci=pcie_scan_all" is a workaround, but we don't want users
to have to do that.
Recognize that PCI-to-PCIe bridges originate links on their secondary
interfaces.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=189361
Fixes: d0751b98dfa3 ("PCI: Add dev->has_secondary_link to track downstream PCIe links")
Tested-by: Blake Moore <blake.moore@men.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org # v4.2+
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
| -rw-r--r-- | drivers/pci/probe.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 993ff22df7ec..3c4e709cf9a1 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -982,6 +982,7 @@ void set_pcie_port_type(struct pci_dev *pdev) pos = pci_find_capability(pdev, PCI_CAP_ID_EXP); if (!pos) return; + pdev->pcie_cap = pos; pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, ®16); pdev->pcie_flags_reg = reg16; @@ -989,13 +990,14 @@ void set_pcie_port_type(struct pci_dev *pdev) pdev->pcie_mpss = reg16 & PCI_EXP_DEVCAP_PAYLOAD; /* - * A Root Port is always the upstream end of a Link. No PCIe - * component has two Links. Two Links are connected by a Switch - * that has a Port on each Link and internal logic to connect the - * two Ports. + * A Root Port or a PCI-to-PCIe bridge is always the upstream end + * of a Link. No PCIe component has two Links. Two Links are + * connected by a Switch that has a Port on each Link and internal + * logic to connect the two Ports. */ type = pci_pcie_type(pdev); - if (type == PCI_EXP_TYPE_ROOT_PORT) + if (type == PCI_EXP_TYPE_ROOT_PORT || + type == PCI_EXP_TYPE_PCIE_BRIDGE) pdev->has_secondary_link = 1; else if (type == PCI_EXP_TYPE_UPSTREAM || type == PCI_EXP_TYPE_DOWNSTREAM) { |