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This is similar to the DSPI instantiation on LS1028A, except that: - The A-011218 erratum has been fixed, so DMA works - The endianness is different, which has implications on XSPI mode Some benchmarking with the following command: spidev_test --device /dev/spidev2.0 --bpw 8 --size 256 --cpha --iter 10000000 --speed 20000000 shows that in DMA mode, it can achieve around 2400 kbps, and in XSPI mode, the same command goes up to 4700 kbps. This is somewhat to be expected, since the DMA buffer size is extremely small at 8 bytes, the winner becomes whomever can prepare the buffers for transmission quicker, and DMA mode has higher overhead there. So XSPI FIFO mode has been chosen as the operating mode for this chip. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Tested-by: Michael Walle <michael@walle.cc> Link: https://lore.kernel.org/r/20200318001603.9650-11-olteanv@gmail.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.