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The chipidea controller doesn't fully support sglist, such as it can not transfer data spanned more dTDs to form a bus packet, so it can only work on very limited cases. The limitations as below: 1. the end address of the first sg buffer must be 4KB aligned. 2. the start and end address of the middle sg buffer must be 4KB aligned. 3. the start address of the first sg buffer must be 4KB aligned. However, not all the use cases violate these limitations. To make the controller compatible with most of the cases, this will try to bounce the problem sglist entries which can be found by sglist_get_invalid_entry(). Then a bounced line buffer (the size will roundup to page size) will be allocated to replace the remaining problem sg entries. The data will be copied between problem sg entries and bounce buffer according to the transfer direction. The bounce buffer will be freed when the request completed. Acked-by: Peter Chen <peter.chen@kernel.com> Signed-off-by: Xu Yang <xu.yang_2@nxp.com> Link: https://lore.kernel.org/r/20240923081203.2851768-3-xu.yang_2@nxp.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 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.