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For delay calculation we need two information: Number of bytes transferred between the DSP and host memory (ALSA buffer) Number of frames transferred between the DSP and external device (link/codec/DMIC/etc). The reason for the different units (bytes vs frames) on host and dai side is that the format on the dai side is decided by the firmware and might not be the same as on the host side, thus the expectation is that the counter reflects the number of frames. The kernel know the host side format and in there we have access to the DMA position which is in bytes. In a simplified way, the DSP caused delay is the difference between the two counters. The existing get_stream_position callback is defined to retrieve the frame counter on the DAI side but it's name is too generic to be intuitive and makes it hard to define a callback for the host side. This patch introduces a new set of callbacks to replace the get_stream_position and define the host side equivalent: get_dai_frame_counter get_host_byte_counter Subsequent patches will remove the old callback. Cc: stable@vger.kernel.org # 6.8 Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com> Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com> Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Link: https://msgid.link/r/20240321130814.4412-7-peter.ujfalusi@linux.intel.com 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.