The pcm_mutex is used to prevent concurrent execution of snd_pcm_ops
callbacks. This works fine most of the cases but it can not handle setups
when the same DAI is used by different rtd, for example:
pcm3168a have two DAIs: one for Playback and one for Capture.
If the codec is connected to a single CPU DAI we need to have two dai_link
to support both playback and capture.

In this case the snd_pcm_ops callbacks can be executed in parallel causing
unexpected races in DAI drivers.

By moving the pcm_mutex up to card level this can be solved
while - hopefully - not breaking other setups.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20190813104532.16669-1-peter.ujfalusi@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>