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d49a303667
This compatible adds the ability for dw spi controller driver to work with the dw spi controller found on Alpine chips. The dw spi controller has an auto-deselect of Chip-Select, in case there is no data inside the Tx FIFO. While working on platforms with Alpine chips, auto-deselect mode causes an issue for some spi devices that can't handle the Chip-Select deselect in the middle of a transaction. It is a normal behavior for a Tx FIFO to be empty in the middle of a transaction, due to busy cpu. In the Alpine chip family an option to change the default behavior was added to the original dw spi controller to prevent this issue of de-asserting Chip-Select once TX FIFO is empty. The change was to allow SW manual control of the Chip-Select. With this change, as long as the Slave Enable Register is asserted, the Chip-Select will be asserted. As a result, it is necessary to deselect the Slave Select Register once the transaction is done. This feature is enabled via a new device compatible string called 'amazon,alpine-dw-apb-ssi'. Once the driver identifies the new compatible string, it enables the hw fixup logic, by writing to a dedicated register found in the IP reserved area and will start manual deselecting the Slave Select Register when the transfer ends. Signed-off-by: Talel Shenhar <talel@amazon.com> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Mark Brown <broonie@kernel.org> |
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| 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.
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.