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Message-Id: <20211004225441.233375-6-pierre-louis.bossart@linux.intel.com>
Date: Mon, 4 Oct 2021 17:54:41 -0500
From: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To: alsa-devel@...a-project.org
Cc: tiwai@...e.de, broonie@...nel.org, vkoul@...nel.org,
Sameer Pujar <spujar@...dia.com>,
Gyeongtaek Lee <gt82.lee@...sung.com>,
Peter Ujfalusi <peter.ujfalusi@...ux.intel.com>,
Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
Liam Girdwood <lgirdwood@...il.com>,
Jaroslav Kysela <perex@...ex.cz>,
Takashi Iwai <tiwai@...e.com>,
linux-kernel@...r.kernel.org (open list)
Subject: [RFC PATCH v2 5/5] 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 mutex.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
---
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 9c00118603e7..6d84e2c60ca8 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 card's dpcm_mutex */
};
#define for_each_dpcm_fe(be, stream, _dpcm) \
diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 6089e0c1bf9f..ed898d83fe17 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -1556,7 +1556,7 @@ 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++;
}
@@ -2051,14 +2051,21 @@ 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))
continue;
+ be->dpcm[stream].be_start++;
+ if (be->dpcm[stream].be_start != 1)
+ continue;
+
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ be->dpcm[stream].be_start--;
goto end;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
break;
@@ -2066,9 +2073,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_SUSPEND))
continue;
+ be->dpcm[stream].be_start++;
+ if (be->dpcm[stream].be_start != 1)
+ continue;
+
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ be->dpcm[stream].be_start--;
goto end;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
break;
@@ -2076,9 +2089,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))
continue;
+ be->dpcm[stream].be_start++;
+ if (be->dpcm[stream].be_start != 1)
+ continue;
+
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ be->dpcm[stream].be_start--;
goto end;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
break;
@@ -2087,12 +2106,18 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
(be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))
continue;
- 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)
continue;
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 end;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_STOP;
break;
@@ -2100,12 +2125,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START)
continue;
- if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
+ be->dpcm[stream].be_start--;
+ if (be->dpcm[stream].be_start != 0)
continue;
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ be->dpcm[stream].be_start++;
goto end;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_SUSPEND;
break;
@@ -2113,12 +2141,15 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START)
continue;
- if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
+ be->dpcm[stream].be_start--;
+ if (be->dpcm[stream].be_start != 0)
continue;
ret = soc_pcm_trigger(be_substream, cmd);
- if (ret)
+ if (ret) {
+ be->dpcm[stream].be_start++;
goto end;
+ }
be->dpcm[stream].state = SND_SOC_DPCM_STATE_PAUSED;
break;
--
2.25.1
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