Linux mainline fork with MSM8998 patches | https://mainline.space | Currently supported devices:
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17e8f0d4ce
Even if a device supports extended config space, i.e., it is a PCI-X Mode 2
or a PCI Express device, the extended space may not be accessible if
there's a conventional PCI bus in the path to it.
We currently figure that out in pci_cfg_space_size() by reading the first
dword of extended config space. On most platforms that returns ~0 data if
the space is inaccessible, but it may set error bits in PCI status
registers, and on some platforms it causes exceptions that we currently
don't recover from.
For example, a PCIe-to-conventional PCI bridge treats config transactions
with a non-zero Extended Register Address as an Unsupported Request on PCIe
and a received Master-Abort on the destination bus (see PCI Express to
PCI/PCI-X Bridge spec, r1.0, sec 4.1.3).
A sample case is a LS1043A CPU (NXP QorIQ Layerscape) platform with the
following bus topology:
LS1043 PCIe Root Port
-> PEX8112 PCIe-to-PCI bridge (doesn't support ext cfg on PCI side)
-> PMC slot connector (for legacy PMC modules)
With a PMC module topology as follows:
PMC connector
-> PCI-to-PCIe bridge
-> PCIe switch (4 ports)
-> 4 PCIe devices (one on each port)
The PCIe devices on the PMC module support extended config space, but we
can't reach it because the PEX8112 can't generate accesses to the extended
space on its secondary bus. Attempts to access it cause Unsupported
Request errors, which result in synchronous aborts on this platform.
To avoid these errors, check whether bridges are capable of generating
extended config space addresses on their secondary interfaces. If they
can't, we restrict devices below the bridge to only the 256-byte
PCI-compatible config space.
Signed-off-by: Gilles Buloz <gilles.buloz@kontron.com>
[bhelgaas: changelog, rework patch so bus_flags testing is all in
pci_bridge_child_ext_cfg_accessible()]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
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.