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Some I3C controllers such as MIPI I3C HCI may pad the last DWORD (32-bit) with stale data from the RX FIFO in DMA transfers if the receive length is not DWORD aligned and when the device DMA is IOMMU mapped. In such a case, a properly sized bounce buffer is required in order to avoid possible data corruption. In a review discussion, proposal was to have a common helpers in I3C core for DMA mapping and bounce buffer handling. Drivers may use the helper i3c_master_dma_map_single() to map a buffer for a DMA transfer. It internally allocates a bounce buffer if buffer is not DMA'able or when the driver requires it for a transfer. Helper i3c_master_dma_unmap_single() does the needed cleanups and data copying from the bounce buffer. Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com> Reviewed-by: Frank Li <Frank.Li@nxp.com> Link: https://lore.kernel.org/r/20250822105630.2820009-2-jarkko.nikula@linux.intel.com Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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 reStructuredText 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.