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Bjorn Helgaas 51ebfc92b7 PCI: Enumerate switches below PCI-to-PCIe bridges
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: d0751b98df ("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+
2017-01-11 09:11:53 -06:00
arch x86/PCI: Ignore _CRS on Supermicro X8DTH-i/6/iF/6F 2017-01-11 09:11:15 -06:00
block ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
certs
crypto
Documentation Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-23 16:54:46 -08:00
drivers PCI: Enumerate switches below PCI-to-PCIe bridges 2017-01-11 09:11:53 -06:00
firmware
fs ktime: Get rid of ktime_equal() 2016-12-25 17:21:23 +01:00
include Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
init mm: add PageWaiters indicating tasks are waiting for a page bit 2016-12-25 11:54:48 -08:00
ipc
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
lib Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
mm mm: add PageWaiters indicating tasks are waiting for a page bit 2016-12-25 11:54:48 -08:00
net ktime: Get rid of ktime_equal() 2016-12-25 17:21:23 +01:00
samples Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-23 16:49:12 -08:00
scripts
security Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sound ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
tools Merge branch 'turbostat' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2016-12-25 14:01:28 -08:00
usr
virt Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
.cocciconfig
.get_maintainer.ignore
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COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Watchdog updates for v4.10 2016-12-24 11:27:45 -08:00
Makefile Linux 4.10-rc1 2016-12-25 16:13:08 -08:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.