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ae76f635d4
DMA_FROM_DEVICE only need to read dma data of memory into CPU cache, so there is no need to clear cache before. Also clear + inv for DMA_FROM_DEVICE won't cause problem, because the memory range for dma won't be touched by software during dma working. Changes for V2: - Remove clr cache and ignore the DMA_TO_DEVICE in _for_cpu. - Change inv to wbinv cache with DMA_FROM_DEVICE in _for_device. Signed-off-by: Guo Ren <ren_guo@c-sky.com> Cc: Arnd Bergmann <arnd@arndb.de>
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.