Unverified Commit 848aedfd authored by Pierre-Louis Bossart's avatar Pierre-Louis Bossart Committed by Mark Brown
Browse files

ASoC: soc-pcm: test refcount before triggering 



On start/pause_release/resume, when more than one FE is connected to
the same BE, it's possible that the trigger is sent more than
once. This is not desirable, we only want to trigger a BE once, which
is straightforward to implement with a refcount.

For stop/pause/suspend, the problem is more complicated: the check
implemented in snd_soc_dpcm_can_be_free_stop() may fail due to a
conceptual deadlock when we trigger the BE before the FE. In this
case, the FE states have not yet changed, so there are corner cases
where the TRIGGER_STOP is never sent - the dual case of start where
multiple triggers might be sent.

This patch suggests an unconditional trigger in all cases, without
checking the FE states, using a refcount protected by the BE PCM
stream lock.

Signed-off-by: default avatarPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: default avatarKai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: default avatarBard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: default avatarRanjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20211207173745.15850-6-pierre-louis.bossart@linux.intel.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent b2ae8066

include/sound/soc-dpcm.h

+2 −0
Original line number Diff line number Diff line
@@ -101,6 +101,8 @@ struct snd_soc_dpcm_runtime { 
	enum snd_soc_dpcm_state state;



	int trigger_pending; /* trigger cmd + 1 if pending, 0 if not */



	int be_start; /* refcount protected by BE stream pcm lock */

};



#define for_each_dpcm_fe(be, stream, _dpcm)				\

sound/soc/soc-pcm.c

+42 −11
Original line number Diff line number Diff line
@@ -1619,7 +1619,7 @@ int dpcm_be_dai_startup(struct snd_soc_pcm_runtime *fe, int stream) 
			be->dpcm[stream].state = SND_SOC_DPCM_STATE_CLOSE;

			goto unwind;

		}



		be->dpcm[stream].be_start = 0;

		be->dpcm[stream].state = SND_SOC_DPCM_STATE_OPEN;

		count++;

	}
@@ -2105,14 +2105,21 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 


		switch (cmd) {

		case SNDRV_PCM_TRIGGER_START:

			if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_PREPARE) &&

			if (!be->dpcm[stream].be_start &&

			    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_PREPARE) &&

			    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_STOP) &&

			    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))

				goto next;



			be->dpcm[stream].be_start++;

			if (be->dpcm[stream].be_start != 1)

				goto next;



			ret = soc_pcm_trigger(be_substream, cmd);

			if (ret)

			if (ret) {

				be->dpcm[stream].be_start--;

				goto next;

			}



			be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;

			break;
@@ -2120,9 +2127,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
			if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_SUSPEND))

				goto next;



			be->dpcm[stream].be_start++;

			if (be->dpcm[stream].be_start != 1)

				goto next;



			ret = soc_pcm_trigger(be_substream, cmd);

			if (ret)

			if (ret) {

				be->dpcm[stream].be_start--;

				goto next;

			}



			be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;

			break;
@@ -2130,9 +2143,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
			if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))

				goto next;



			be->dpcm[stream].be_start++;

			if (be->dpcm[stream].be_start != 1)

				goto next;



			ret = soc_pcm_trigger(be_substream, cmd);

			if (ret)

			if (ret) {

				be->dpcm[stream].be_start--;

				goto next;

			}



			be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;

			break;
@@ -2141,12 +2160,18 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
			    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))

				goto next;



			if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))

			if (be->dpcm[stream].state == SND_SOC_DPCM_STATE_START)

				be->dpcm[stream].be_start--;



			if (be->dpcm[stream].be_start != 0)

				goto next;



			ret = soc_pcm_trigger(be_substream, cmd);

			if (ret)

			if (ret) {

				if (be->dpcm[stream].state == SND_SOC_DPCM_STATE_START)

					be->dpcm[stream].be_start++;

				goto next;

			}



			be->dpcm[stream].state = SND_SOC_DPCM_STATE_STOP;

			break;
@@ -2154,12 +2179,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
			if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START)

				goto next;



			if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))

			be->dpcm[stream].be_start--;

			if (be->dpcm[stream].be_start != 0)

				goto next;



			ret = soc_pcm_trigger(be_substream, cmd);

			if (ret)

			if (ret) {

				be->dpcm[stream].be_start++;

				goto next;

			}



			be->dpcm[stream].state = SND_SOC_DPCM_STATE_SUSPEND;

			break;
@@ -2167,12 +2195,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
			if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START)

				goto next;



			if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))

			be->dpcm[stream].be_start--;

			if (be->dpcm[stream].be_start != 0)

				goto next;



			ret = soc_pcm_trigger(be_substream, cmd);

			if (ret)

			if (ret) {

				be->dpcm[stream].be_start++;

				goto next;

			}



			be->dpcm[stream].state = SND_SOC_DPCM_STATE_PAUSED;

			break;