596a5a58e8
This is rougly equivalent to ca0e68e21a (drm/prime: skip CPU sync
in map/unmap dma_buf). The contig memory allocated is already device
coherent memory, so there is no point in doing a CPU sync when
mapping it to another device. Also most importers currently cache
the mapping so the CPU sync would only happen on the first import,
so we are better off with not pretending to do a cache synchronization
at all.
This gets rid of a lot of CPU overhead in uses where those dma-bufs
are regularily imported and detached again, like Weston is currently
doing in the DRM compositor.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil-cisco@xs4all.nl: fix checkpatch warnings]
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@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.