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Date: Tue, 17 Aug 2021 11:40:54 -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,
liam.r.girdwood@...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 2/2] 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: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
---
include/sound/soc-dpcm.h | 2 ++
sound/soc/soc-pcm.c | 46 ++++++++++++++++++++++++++++++++++++----
2 files changed, 44 insertions(+), 4 deletions(-)
diff --git a/include/sound/soc-dpcm.h b/include/sound/soc-dpcm.h
index e296a3949b18..6cc751002da7 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 dpcm_lock */
};
#define for_each_dpcm_fe(be, stream, _dpcm) \
diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 0717f39d2eec..b2440f2f9bf5 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -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;
}
--
2.25.1
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