mainlining shenanigans
6c1c26ecd9
This patch adds logic in the driver to transmit SPI buffers that use bits_per_word=8 with a higher bits_per_word count (multiple of 8). Currently the following (most common) modes are implemented: - 8 bits_per_word on 32-bit capable controllers - 8 bits_per_word on 16-bit capable controllers - 16 bits_per_word on 32-bit capable controllers Transfers which are not accelerated are transferred with a hardware bits_per_word value equal to the one of the SPI transfer. The difference from just extending bits_per_word=32 at the spi_device driver level is that endianness is different - the SPI core wants to treat bits_per_word=32 buffers as arrays of u32 (i.e. words in host CPU endianness). So to preserve endianness when clumping 8x4 bits into 32-bit words, one must perform conversion between CPU and standard (big) endianness. All appearances (both on the wire as well as in the buffers presented to the peripheral driver) are preserved, just that accesses to the PUSHR and POPR registers are now more efficient, since the same number of reads/writes can now carry more data (2x more data on TX, 4x more data on RX). Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Link: https://lore.kernel.org/r/20200304220044.11193-10-olteanv@gmail.com Signed-off-by: Mark Brown <broonie@kernel.org> |
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.