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: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
---
include/sound/soc-dpcm.h | 2 ++
sound/soc/soc-pcm.c | 53 +++++++++++++++++++++++++++++++---------
2 files changed, 44 insertions(+), 11 deletions(-)
diff --git a/include/sound/soc-dpcm.h b/include/sound/soc-dpcm.h
index 8ed40b8f3da8..9464c588f71d 100644
--- a/include/sound/soc-dpcm.h
+++ b/include/sound/soc-dpcm.h
@@ -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) \
diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index d115e9409c14..1967980d0f79 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -1600,7 +1600,7 @@ 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++;
}
@@ -2096,14 +2096,21 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
snd_soc_dpcm_be_lock_irqsave(be, stream, flags);
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 unlock_be;
+ be->dpcm[stream].be_start++;
+ if (be->dpcm[stream].be_start != 1)
+ goto unlock_be;
+
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ be->dpcm[stream].be_start--;
goto unlock_be;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
break;
@@ -2111,9 +2118,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_SUSPEND))
goto unlock_be;
+ be->dpcm[stream].be_start++;
+ if (be->dpcm[stream].be_start != 1)
+ goto unlock_be;
+
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ be->dpcm[stream].be_start--;
goto unlock_be;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
break;
@@ -2121,9 +2134,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))
goto unlock_be;
+ be->dpcm[stream].be_start++;
+ if (be->dpcm[stream].be_start != 1)
+ goto unlock_be;
+
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ be->dpcm[stream].be_start--;
goto unlock_be;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
break;
@@ -2132,12 +2151,18 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
(be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))
goto unlock_be;
- if (!snd_soc_dpcm_can_be_free_stop_locked(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 unlock_be;
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 unlock_be;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_STOP;
break;
@@ -2145,12 +2170,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START)
goto unlock_be;
- if (!snd_soc_dpcm_can_be_free_stop_locked(fe, be, stream))
+ be->dpcm[stream].be_start--;
+ if (be->dpcm[stream].be_start != 0)
goto unlock_be;
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ be->dpcm[stream].be_start++;
goto unlock_be;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_SUSPEND;
break;
@@ -2158,12 +2186,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START)
goto unlock_be;
- if (!snd_soc_dpcm_can_be_free_stop_locked(fe, be, stream))
+ be->dpcm[stream].be_start--;
+ if (be->dpcm[stream].be_start != 0)
goto unlock_be;
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ be->dpcm[stream].be_start++;
goto unlock_be;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_PAUSED;
break;
--
2.25.1
