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A port of a CXL host bridge links to the bridge's ACPI device
(&adev->dev) with its corresponding uport/dport device (uport_dev and
dport_dev respectively). The device is not a direct parent device in
the PCI topology as pdev->dev.parent points to a PCI bridge's (struct
pci_host_bridge) device. The following CXL memory device hierarchy
would be valid for an endpoint once an RCD EP would be enabled (note
this will be done in a later patch):
VH mode:
cxlmd->dev.parent->parent
^^^\^^^^^^\ ^^^^^^\
\ \ pci_dev (Type 1, Downstream Port)
\ pci_dev (Type 0, PCI Express Endpoint)
cxl mem device
RCD mode:
cxlmd->dev.parent->parent
^^^\^^^^^^\ ^^^^^^\
\ \ pci_host_bridge
\ pci_dev (Type 0, RCiEP)
cxl mem device
In VH mode a downstream port is created by port enumeration and thus
always exists.
Now, in RCD mode the host bridge also already exists but it references
to an ACPI device. A port lookup by the PCI device's parent device
will fail as a direct link to the registered port is missing. The ACPI
device of the bridge must be determined first.
To prevent this, change port registration of a CXL host to use the
bridge device instead. Do this also for the VH case as port topology
will better reflect the PCI topology then.
Signed-off-by: Robert Richter <rrichter@amd.com>
[djbw: rebase on brige mocking]
Reviewed-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/166993043978.1882361.16238060349889579369.stgit@dwillia2-xfh.jf.intel.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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.
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.