4fc2d3cd6d
When DMA is used for TX and RX by serial driver, it should pass the DMA device pointer to DMA API instead of UART device pointer. DMA device should be used for DMA API because only the DMA device is aware of how the device connects to the memory. There might be an extra level of address translation due to a SMMU attached to the DMA device. When serial device is used for DMA API, the DMA API will have no clue of the SMMU attached to the DMA device. This patch is necessary to fix the SMMU page faults which is observed when a DMA(with SMMU enabled) is attached to UART for transfer. Acked-by: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> Signed-off-by: Tamseel Shams <m.shams@samsung.com> Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com> Link: https://lore.kernel.org/r/20210629045902.48912-1-m.shams@samsung.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.