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The IProc host controller has I/O memory windows allocated in
the AXI memory map that can be used to address PCI I/O memory
space.
Mapping from AXI memory windows to PCI outbound memory windows is
carried out in the host controller through OARR/OMAP registers pairs
that permit to define power of two region size AXI<->PCI mappings, the
smallest of which is 128MB.
Current code enables AXI memory window to PCI outbound memory window
mapping only for AXI windows matching one of the OARR/OMAP window sizes,
that are SoC dependent and the smallest of which is 128MB.
Some SoCs implementing the IProc host controller have a 32-bit AXI
memory window into PCI I/O memory space, eg:
Base address | Size
-----------------------------
(1) 0x42000000 | 0x2000000
(2) 0x400000000 | 0x80000000
but its size (32MB - (1) above) is smaller than the smallest AXI<->PCI
region size provided by OARR (128MB), so the current driver rejects
mappings for the 32-bit region making the IProc host controller driver
unusable on 32-bit systems.
However, there is no reason why the 32-bit I/O memory window cannot be
enabled by mapping it through an OARR/OMAP region bigger in size (ie
32-bit AXI window size is 32MB but can be mapped using a 128MB OARR/OMAP
region).
Allow outbound window configuration of I/O memory windows that
are smaller in size than the host controller OARR/OMAP region, so
that the 32-bit AXI memory window can actually be enabled,
making the IProc host controller operational on 32-bit systems.
Link: https://lore.kernel.org/linux-pci/1551415936-30174-3-git-send-email-srinath.mannam@broadcom.com/
Signed-off-by: Srinath Mannam <srinath.mannam@broadcom.com>
Signed-off-by: Abhishek Shah <abhishek.shah@broadcom.com>
Signed-off-by: Ray Jui <ray.jui@broadcom.com>
[lorenzo.pieralisi@arm.com: rewrote the commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Scott Branden <scott.branden@broadcom.com>
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| fs | ||
| include | ||
| init | ||
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| .clang-format | ||
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| 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.
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.