09c04466ce
Add dma mode support for LPSPI. Any frame longer than half txfifosize will be sent by dma mode. For now, there are some limits: 1. The maximum transfer speed in master mode depends on the slave device, at least 40MHz(tested by spi-nor on 8qm-lpddr4-arm2 base board); 2. The maximum transfer speed in slave mode is 15MHz(imx7ulp), 22MHz(8qm/qxp). In order to reach the maximum speed which is mentioned in datasheet, the load of connect wires between master and slave should be less than 15pF. Signed-off-by: Clark Wang <xiaoning.wang@nxp.com> Acked-by: Fugang Duan <Fugang.duan@nxp.com> Signed-off-by: Mark Brown <broonie@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.