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SPI transfer tx/rx buffers must be DMA-safe and the structure documentation clearly states this. Data declared on the system stack isn't DMA-safe [1]. Instead at least kernel memory should be used for the buffers. In order to fix this here we can create the buffers at the device probing stage and use them without any synchronization, since batch read/write methods are called from non-reentrant contexts - either from rx-event IRQ threaded handler or from the tx workqueue item. [1] Documentation/DMA-API-HOWTO.txt Signed-off-by: Serge Semin <fancer.lancer@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.