ASoC: SOF: ipc4-pcm: Implement pipeline trigger reference counting

Use the started_count and paused_count to implement reference counting
when making decisions to start/stop/pause pipelines during the FE DAI
trigger. This is necessary to trigger the shared pipelines in the FE DAI
trigger properly.

With IPC4, the FE trigger will issue multiple pipeline state changes,
and the triggers are propagated downstream to connected pipelines by
the SOF driver - not the firmware. This creates a window for race
conditions where an FE trigger preempts another one, which results
in inconsistent pipeline states and refcounts.

This patch introduces a mutex lock for the pcm trigger that guarantees
that IPC4 state and resources are accessed in a serialized manner.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20230127120031.10709-15-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/sound/soc/sof/ipc4.c b/sound/soc/sof/ipc4.c
index 74cd7e956019..fb4760ae593f 100644
--- a/sound/soc/sof/ipc4.c
+++ b/sound/soc/sof/ipc4.c
@@ -662,6 +662,8 @@ static int sof_ipc4_init(struct snd_sof_dev *sdev)
 {
 	struct sof_ipc4_fw_data *ipc4_data = sdev->private;
 
+	mutex_init(&ipc4_data->trigger_mutex);
+
 	xa_init_flags(&ipc4_data->fw_lib_xa, XA_FLAGS_ALLOC);
 
 	return 0;