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commit 4bbda9421f316efdaef5dbf642e24925ef7de130 upstream. The blsp_dma controller is shared between the different subsystems, which is why it is already initialized by the firmware. We should not reinitialize it from Linux to avoid potential other users of the DMA engine to misbehave. In mainline this can be described using the "qcom,controlled-remotely" property. In the downstream/vendor kernel from Qualcomm there is an opposite "qcom,managed-locally" property. This property is *not* set for the qcom,sps-dma@7884000 [1] so adding "qcom,controlled-remotely" upstream matches the behavior of the downstream/vendor kernel. Adding this seems to fix some weird issues with UART where both input/output becomes garbled with certain obscure firmware versions on some devices. [1]: https://git.codelinaro.org/clo/la/kernel/msm-3.10/-/blob/LA.BR.1.2.9.1-02310-8x16.0/arch/arm/boot/dts/qcom/msm8939-common.dtsi#L866-872 Cc: stable@vger.kernel.org # 6.5 Fixes: 61550c6c156c ("arm64: dts: qcom: Add msm8939 SoC") Signed-off-by: Stephan Gerhold <stephan@gerhold.net> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> Link: https://lore.kernel.org/r/20231204-msm8916-blsp-dma-remote-v1-2-3e49c8838c8d@gerhold.net Signed-off-by: Bjorn Andersson <andersson@kernel.org> 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.