Unverified Commit 6479f758 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 a spinlock.

Signed-off-by: default avatarPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Message-Id: <20210817164054.250028-3-pierre-louis.bossart@linux.intel.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 0c75fc71

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 dpcm_lock */

};



#define for_each_dpcm_fe(be, stream, _dpcm)				\

sound/soc/soc-pcm.c

+42 −4
Original line number Diff line number Diff line
@@ -1534,7 +1534,7 @@ 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++;

	}
@@ -2001,6 +2001,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
	int ret = 0;

	unsigned long flags;

	enum snd_soc_dpcm_state state;

	bool do_trigger;



	for_each_dpcm_be(fe, stream, dpcm) {

		struct snd_pcm_substream *be_substream;
@@ -2015,6 +2016,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
		dev_dbg(be->dev, "ASoC: trigger BE %s cmd %d\n",

			be->dai_link->name, cmd);



		do_trigger = false;

		switch (cmd) {

		case SNDRV_PCM_TRIGGER_START:

			spin_lock_irqsave(&fe->card->dpcm_lock, flags);
@@ -2025,13 +2027,20 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
				continue;

			}

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

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

				do_trigger = true;

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

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

			spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);



			if (!do_trigger)

				continue;



			ret = soc_pcm_trigger(be_substream, cmd);

			if (ret) {

				spin_lock_irqsave(&fe->card->dpcm_lock, flags);

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

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

				spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);

				goto end;

			}
@@ -2045,13 +2054,20 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
			}



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

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

				do_trigger = true;

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

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

			spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);



			if (!do_trigger)

				continue;



			ret = soc_pcm_trigger(be_substream, cmd);

			if (ret) {

				spin_lock_irqsave(&fe->card->dpcm_lock, flags);

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

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

				spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);

				goto end;

			}
@@ -2065,13 +2081,20 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
			}



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

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

				do_trigger = true;

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

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

			spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);



			if (!do_trigger)

				continue;



			ret = soc_pcm_trigger(be_substream, cmd);

			if (ret) {

				spin_lock_irqsave(&fe->card->dpcm_lock, flags);

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

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

				spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);

				goto end;

			}
@@ -2084,9 +2107,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
				spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);

				continue;

			}

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

			     be->dpcm[stream].be_start == 1) ||

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

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

				do_trigger = true;

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

			spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);



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

			if (!do_trigger)

				continue;



			spin_lock_irqsave(&fe->card->dpcm_lock, flags);
@@ -2098,6 +2127,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
			if (ret) {

				spin_lock_irqsave(&fe->card->dpcm_lock, flags);

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

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

				spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);

				goto end;

			}
@@ -2109,9 +2139,12 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
				spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);

				continue;

			}

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

				do_trigger = true;

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

			spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);



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

			if (!do_trigger)

				continue;



			spin_lock_irqsave(&fe->card->dpcm_lock, flags);
@@ -2123,6 +2156,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
			if (ret) {

				spin_lock_irqsave(&fe->card->dpcm_lock, flags);

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

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

				spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);

				goto end;

			}
@@ -2134,9 +2168,12 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
				spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);

				continue;

			}

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

				do_trigger = true;

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

			spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);



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

			if (!do_trigger)

				continue;



			spin_lock_irqsave(&fe->card->dpcm_lock, flags);
@@ -2148,6 +2185,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream, 
			if (ret) {

				spin_lock_irqsave(&fe->card->dpcm_lock, flags);

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

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

				spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);

				goto end;

			}