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5fbc2c2bfa
Add a simple helper to read data with the CPU from the page of a GEM object. Do the read either via a kmap if the object has struct pages or an iomap otherwise. This is needed by the next patch, reading a u64 value from the object (w/o requiring the obj to be mapped to the GPU). Suggested by Chris. v2 (Chris): - Sanitize the type and order of func params. - Avoid consts requiring too many casts. - Use BUG_ON instead of WARN_ON, simplify the conditions. - Fix __iomem sparse errors. - Leave locking/syncing/pinning up to the caller, require only that the caller has pinned the object pages. - Check for iomem backing store before reading via an iomap. v3: - Fix offset passed to io_mapping_map_wc() missing a mem.region.start delta. (Chris, Matthew) Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Matthew Auld <matthew.william.auld@gmail.com> Signed-off-by: Imre Deak <imre.deak@intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/msgid/20210120213834.1435710-1-imre.deak@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.