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The only information we use in the 8-word version of the hardware DMA descriptor that is not present in the 4-word version is the transfer type, aka. the ID of the source or recipient device. Since the transfer type will never change for a DMA channel in use, we can just set it once for all in the corresponding DMA register before starting any transfer. This has several benefits: * the driver will handle twice as many hardware DMA descriptors; * the driver is closer to support the JZ4740, which only supports 4-word hardware DMA descriptors; * the JZ4770 SoC needs the transfer type to be set in the corresponding DMA register anyway, even if 8-word descriptors are in use. Signed-off-by: Paul Cercueil <paul@crapouillou.net> Tested-by: Mathieu Malaterre <malat@debian.org> Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> Signed-off-by: Vinod Koul <vkoul@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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.