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The DWC PCIe core contains various separate register spaces: DBI, DBI2, ATU, DMA, etc. The relationship between the addresses of these register spaces is entirely determined by the implementation of the IP block, not by the IP block design itself. Hence, the DWC driver must not make assumptions that one register space can be accessed at a fixed offset from any other register space. To avoid such assumptions, introduce an explicit/separate register pointer for the ATU register space. In particular, the current assumption is not valid for NVIDIA's T194 SoC. The ATU register space is only used on systems that require unrolled ATU access. This property is detected at run-time for host controllers, and when this is detected, this patch provides a default value for atu_base that matches the previous assumption re: register layout. An alternative would be to update all drivers for HW that requires unrolled access to explicitly set atu_base. However, it's hard to tell which drivers would require atu_base to be set. The unrolled property is not detected for endpoint systems, and so any endpoint driver that requires unrolled access must explicitly set the iatu_unroll_enabled flag (none do at present), and so a check is added to require the driver to also set atu_base while at it. Signed-off-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com> Acked-by: Vidya Sagar <vidyas@nvidia.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.