377301bfb6
Set allow_cache_hints to 1 for the vb2_queue source and destination queues in the mediatek vcodec V4L2 driver. This allows us to allocate buffers with the V4L2_MEMORY_FLAG_NON_COHERENT set. On Mediatek SoCs, this enables caching for this memory, which vastly improves performance when being read from CPU. Read performance for these buffers is in turn important for detiling MM21 video frames in userspace software, such as libyuv or gstreamer. This change should be safe from race conditions since videobuf2 already invalidates or flushes the appropriate cache lines in its prepare() and finish() methods. Tested on a MT8183 SoC. Resulted in both correct detiling and a 10X speedup. Signed-off-by: Justin Green <greenjustin@chromium.org> Suggested-by: Nicolas Dufresne <nicolas.dufresne@collabora.com> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
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.