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-rw-r--r--Documentation/sound/kernel-api/writing-an-alsa-driver.rst17
-rw-r--r--include/sound/pcm.h14
-rw-r--r--include/uapi/sound/asound.h11
-rw-r--r--sound/core/pcm_lib.c86
-rw-r--r--sound/core/pcm_local.h3
-rw-r--r--sound/core/pcm_native.c6
6 files changed, 66 insertions, 71 deletions
diff --git a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
index a368529e8ed3..e37d9dba320d 100644
--- a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
+++ b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
@@ -1577,14 +1577,19 @@ are the contents of this file:
unsigned int period_step;
unsigned int sleep_min; /* min ticks to sleep */
snd_pcm_uframes_t start_threshold;
- snd_pcm_uframes_t stop_threshold;
- snd_pcm_uframes_t silence_threshold; /* Silence filling happens when
- noise is nearest than this */
- snd_pcm_uframes_t silence_size; /* Silence filling size */
+ /*
+ * The following two thresholds alleviate playback buffer underruns; when
+ * hw_avail drops below the threshold, the respective action is triggered:
+ */
+ snd_pcm_uframes_t stop_threshold; /* - stop playback */
+ snd_pcm_uframes_t silence_threshold; /* - pre-fill buffer with silence */
+ snd_pcm_uframes_t silence_size; /* max size of silence pre-fill; when >= boundary,
+ * fill played area with silence immediately */
snd_pcm_uframes_t boundary; /* pointers wrap point */
- snd_pcm_uframes_t silenced_start;
- snd_pcm_uframes_t silenced_size;
+ /* internal data of auto-silencer */
+ snd_pcm_uframes_t silence_start; /* starting pointer to silence area */
+ snd_pcm_uframes_t silence_filled; /* size filled with silence */
snd_pcm_sync_id_t sync; /* hardware synchronization ID */
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 27040b472a4f..19f564606ac4 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -378,18 +378,18 @@ struct snd_pcm_runtime {
unsigned int rate_den;
unsigned int no_period_wakeup: 1;
- /* -- SW params -- */
- int tstamp_mode; /* mmap timestamp is updated */
+ /* -- SW params; see struct snd_pcm_sw_params for comments -- */
+ int tstamp_mode;
unsigned int period_step;
snd_pcm_uframes_t start_threshold;
snd_pcm_uframes_t stop_threshold;
- snd_pcm_uframes_t silence_threshold; /* Silence filling happens when
- noise is nearest than this */
- snd_pcm_uframes_t silence_size; /* Silence filling size */
- snd_pcm_uframes_t boundary; /* pointers wrap point */
+ snd_pcm_uframes_t silence_threshold;
+ snd_pcm_uframes_t silence_size;
+ snd_pcm_uframes_t boundary;
+ /* internal data of auto-silencer */
snd_pcm_uframes_t silence_start; /* starting pointer to silence area */
- snd_pcm_uframes_t silence_filled; /* size filled with silence */
+ snd_pcm_uframes_t silence_filled; /* already filled part of silence area */
union snd_pcm_sync_id sync; /* hardware synchronization ID */
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index 7eecc99ddef7..0aa955aa8246 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -429,9 +429,14 @@ struct snd_pcm_sw_params {
snd_pcm_uframes_t avail_min; /* min avail frames for wakeup */
snd_pcm_uframes_t xfer_align; /* obsolete: xfer size need to be a multiple */
snd_pcm_uframes_t start_threshold; /* min hw_avail frames for automatic start */
- snd_pcm_uframes_t stop_threshold; /* min avail frames for automatic stop */
- snd_pcm_uframes_t silence_threshold; /* min distance from noise for silence filling */
- snd_pcm_uframes_t silence_size; /* silence block size */
+ /*
+ * The following two thresholds alleviate playback buffer underruns; when
+ * hw_avail drops below the threshold, the respective action is triggered:
+ */
+ snd_pcm_uframes_t stop_threshold; /* - stop playback */
+ snd_pcm_uframes_t silence_threshold; /* - pre-fill buffer with silence */
+ snd_pcm_uframes_t silence_size; /* max size of silence pre-fill; when >= boundary,
+ * fill played area with silence immediately */
snd_pcm_uframes_t boundary; /* pointers wrap point */
unsigned int proto; /* protocol version */
unsigned int tstamp_type; /* timestamp type (req. proto >= 2.0.12) */
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index af1eb136feb0..d21c73944efd 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -42,70 +42,56 @@ static int fill_silence_frames(struct snd_pcm_substream *substream,
*
* when runtime->silence_size >= runtime->boundary - fill processed area with silence immediately
*/
-void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_uframes_t new_hw_ptr)
+void snd_pcm_playback_silence(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
- snd_pcm_uframes_t frames, ofs, transfer;
+ snd_pcm_uframes_t appl_ptr = READ_ONCE(runtime->control->appl_ptr);
+ snd_pcm_sframes_t added, hw_avail, frames;
+ snd_pcm_uframes_t noise_dist, ofs, transfer;
int err;
+ added = appl_ptr - runtime->silence_start;
+ if (added) {
+ if (added < 0)
+ added += runtime->boundary;
+ if (added < runtime->silence_filled)
+ runtime->silence_filled -= added;
+ else
+ runtime->silence_filled = 0;
+ runtime->silence_start = appl_ptr;
+ }
+
+ // This will "legitimately" turn negative on underrun, and will be mangled
+ // into a huge number by the boundary crossing handling. The initial state
+ // might also be not quite sane. The code below MUST account for these cases.
+ hw_avail = appl_ptr - runtime->status->hw_ptr;
+ if (hw_avail < 0)
+ hw_avail += runtime->boundary;
+
+ noise_dist = hw_avail + runtime->silence_filled;
if (runtime->silence_size < runtime->boundary) {
- snd_pcm_sframes_t noise_dist, n;
- snd_pcm_uframes_t appl_ptr = READ_ONCE(runtime->control->appl_ptr);
- if (runtime->silence_start != appl_ptr) {
- n = appl_ptr - runtime->silence_start;
- if (n < 0)
- n += runtime->boundary;
- if ((snd_pcm_uframes_t)n < runtime->silence_filled)
- runtime->silence_filled -= n;
- else
- runtime->silence_filled = 0;
- runtime->silence_start = appl_ptr;
- }
- if (runtime->silence_filled >= runtime->buffer_size)
- return;
- noise_dist = snd_pcm_playback_hw_avail(runtime) + runtime->silence_filled;
- if (noise_dist >= (snd_pcm_sframes_t) runtime->silence_threshold)
- return;
frames = runtime->silence_threshold - noise_dist;
+ if (frames <= 0)
+ return;
if (frames > runtime->silence_size)
frames = runtime->silence_size;
} else {
- if (new_hw_ptr == ULONG_MAX) { /* initialization */
- snd_pcm_sframes_t avail = snd_pcm_playback_hw_avail(runtime);
- if (avail > runtime->buffer_size)
- avail = runtime->buffer_size;
- runtime->silence_filled = avail > 0 ? avail : 0;
- runtime->silence_start = (runtime->status->hw_ptr +
- runtime->silence_filled) %
- runtime->boundary;
- } else {
- ofs = runtime->status->hw_ptr;
- frames = new_hw_ptr - ofs;
- if ((snd_pcm_sframes_t)frames < 0)
- frames += runtime->boundary;
- runtime->silence_filled -= frames;
- if ((snd_pcm_sframes_t)runtime->silence_filled < 0) {
- runtime->silence_filled = 0;
- runtime->silence_start = new_hw_ptr;
- } else {
- runtime->silence_start = ofs;
- }
- }
- frames = runtime->buffer_size - runtime->silence_filled;
+ frames = runtime->buffer_size - noise_dist;
+ if (frames <= 0)
+ return;
}
+
if (snd_BUG_ON(frames > runtime->buffer_size))
return;
- if (frames == 0)
- return;
- ofs = runtime->silence_start % runtime->buffer_size;
- while (frames > 0) {
+ ofs = (runtime->silence_start + runtime->silence_filled) % runtime->buffer_size;
+ do {
transfer = ofs + frames > runtime->buffer_size ? runtime->buffer_size - ofs : frames;
err = fill_silence_frames(substream, ofs, transfer);
snd_BUG_ON(err < 0);
runtime->silence_filled += transfer;
frames -= transfer;
ofs = 0;
- }
+ } while (frames > 0);
snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_DEVICE);
}
@@ -439,10 +425,6 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
return 0;
}
- if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
- runtime->silence_size > 0)
- snd_pcm_playback_silence(substream, new_hw_ptr);
-
if (in_interrupt) {
delta = new_hw_ptr - runtime->hw_ptr_interrupt;
if (delta < 0)
@@ -460,6 +442,10 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
runtime->hw_ptr_wrap += runtime->boundary;
}
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
+ runtime->silence_size > 0)
+ snd_pcm_playback_silence(substream);
+
update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp);
return snd_pcm_update_state(substream, runtime);
diff --git a/sound/core/pcm_local.h b/sound/core/pcm_local.h
index ecb21697ae3a..42fe3a4e9154 100644
--- a/sound/core/pcm_local.h
+++ b/sound/core/pcm_local.h
@@ -29,8 +29,7 @@ int snd_pcm_update_state(struct snd_pcm_substream *substream,
struct snd_pcm_runtime *runtime);
int snd_pcm_update_hw_ptr(struct snd_pcm_substream *substream);
-void snd_pcm_playback_silence(struct snd_pcm_substream *substream,
- snd_pcm_uframes_t new_hw_ptr);
+void snd_pcm_playback_silence(struct snd_pcm_substream *substream);
static inline snd_pcm_uframes_t
snd_pcm_avail(struct snd_pcm_substream *substream)
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 94185267a7b9..3d0c4a5b701b 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -958,7 +958,7 @@ static int snd_pcm_sw_params(struct snd_pcm_substream *substream,
if (snd_pcm_running(substream)) {
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
runtime->silence_size > 0)
- snd_pcm_playback_silence(substream, ULONG_MAX);
+ snd_pcm_playback_silence(substream);
err = snd_pcm_update_state(substream, runtime);
}
snd_pcm_stream_unlock_irq(substream);
@@ -1455,7 +1455,7 @@ static void snd_pcm_post_start(struct snd_pcm_substream *substream,
__snd_pcm_set_state(runtime, state);
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
runtime->silence_size > 0)
- snd_pcm_playback_silence(substream, ULONG_MAX);
+ snd_pcm_playback_silence(substream);
snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSTART);
}
@@ -1916,7 +1916,7 @@ static void snd_pcm_post_reset(struct snd_pcm_substream *substream,
runtime->control->appl_ptr = runtime->status->hw_ptr;
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
runtime->silence_size > 0)
- snd_pcm_playback_silence(substream, ULONG_MAX);
+ snd_pcm_playback_silence(substream);
snd_pcm_stream_unlock_irq(substream);
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-02 17:38:41 +0100