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Under heavy load resulting in high interrupt latencies, it is possible for imx UART requests to completely fill DMA buffer. When DMA channel is triggered and no SDMA owned buffer is available, SDMA stops. Thanks to the autoRTS feature, there is no data loss due to the SDMA stop if the UART is using hardware flow control. According to DMA Engine API Guide, DMA cyclic operation is performed until explicitly stopped. Restart the buffer after handling channel loop if the channel was stopped by SDMA. Signed-off-by: Tomasz Moń <tomasz.mon@camlingroup.com> Link: https://lore.kernel.org/r/20220117091955.1038937-1-tomasz.mon@camlingroup.com Signed-off-by: Vinod Koul <vkoul@kernel.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.