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On Chromebooks based on Mediatek MT8195 or MT8188, the audio frontend (AFE) is limited to accessing a very small window (1 MiB) of memory, which is described as a reserved memory region in the device tree. On these two platforms, the maximum buffer size is given as 512 KiB. The MediaTek common code uses the same value for preallocations. This means that only the first two PCM substreams get preallocations, and then the whole space is exhausted, barring any other substreams from working. Since the substreams used are not always the first two, this means audio won't work correctly. This is observed on the MT8188 Geralt Chromebooks, on which the "mediatek,dai-link" property was dropped when it was upstreamed. That property causes the driver to only register the PCM substreams listed in the property, and in the order given. Instead of trying to compute an optimal value and figuring out which streams are used, simply disable preallocation. The PCM buffers are managed by the core and are allocated and released on the fly. There should be no impact to any of the other MediaTek platforms. Signed-off-by: Chen-Yu Tsai <wenst@chromium.org> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Link: https://patch.msgid.link/20241219105303.548437-1-wenst@chromium.org Signed-off-by: Mark Brown <broonie@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 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.