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631b2e7318
Add a way for firmware to tell the OS that ATS is supported by the PCI root complex. An endpoint with ATS enabled may send Translation Requests and Translated Memory Requests, which look just like Normal Memory Requests with a non-zero AT field. So a root controller that ignores the AT field may simply forward the request to the IOMMU as a Normal Memory Request, which could end badly. In any case, the endpoint will be unusable. The ats-supported property allows the OS to only enable ATS in endpoints if the root controller can handle ATS requests. Only add the property to pcie-host-ecam-generic for the moment. For non-generic root controllers, availability of ATS can be inferred from the compatible string. Link: https://lore.kernel.org/linux-pci/20240607105415.2501934-3-jean-philippe@linaro.org Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Liviu Dudau <liviu.dudau@arm.com> Reviewed-by: Nicolin Chen <nicolinc@nvidia.com> Reviewed-by: Rob Herring <robh@kernel.org> Reviewed-by: Robin Murphy <robin.murphy@arm.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 reStructuredText 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.