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When application goes through SUSPEND/STOP->PREPARE->START cycle, we should always reprogram the SOF device to start DMA from a known state so that hw_ptr/appl_ptrs remain valid. This is expected by ALSA core as it resets the buffer state as part of prepare (see snd_pcm_do_prepare()). Fix the issue by forcing reconfiguration of the FW with STREAM_PCM_PARAMS in prepare(). Use combined logic to handle prepare and the existing flow to reprogram hw-params after system suspend. Without the fix, first call to pcm pointer() will return an invalid hw_ptr and application may immediately observe XRUN status, unless "start_threshold" SW parameter is set to maximum value by the application. Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Link: https://lore.kernel.org/r/20190722141402.7194-3-pierre-louis.bossart@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 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.