Turns out that we cannot rely on the application pointer being updated in top-up mode, as its primary purpose is to remain operational in free-running mode as used by dmix.
So we logically revert some bits from commit 9f656705c5faa ("ALSA: pcm: rewrite snd_pcm_playback_silence()"), but we retain the bug fixes and try to make the code paths congruent.
Reported-by: Jeff Chua jeff.chua.linux@gmail.com Signed-off-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de --- sound/core/pcm_lib.c | 82 +++++++++++++++++++++++++++-------------- sound/core/pcm_local.h | 3 +- sound/core/pcm_native.c | 6 +-- 3 files changed, 60 insertions(+), 31 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index d21c73944efd..cd5f2ef14ab4 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -42,41 +42,69 @@ 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) +void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_uframes_t new_hw_ptr) { struct snd_pcm_runtime *runtime = substream->runtime; - snd_pcm_uframes_t appl_ptr = READ_ONCE(runtime->control->appl_ptr); - snd_pcm_sframes_t added, hw_avail, frames; + snd_pcm_sframes_t 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_uframes_t appl_ptr = READ_ONCE(runtime->control->appl_ptr); + snd_pcm_sframes_t 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; + } + + if (new_hw_ptr == ULONG_MAX) // initialization + new_hw_ptr = runtime->status->hw_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 - new_hw_ptr; + if (hw_avail < 0) + hw_avail += runtime->boundary; + + noise_dist = hw_avail + runtime->silence_filled; frames = runtime->silence_threshold - noise_dist; if (frames <= 0) return; if (frames > runtime->silence_size) frames = runtime->silence_size; } else { - frames = runtime->buffer_size - noise_dist; + // This filling mode aims at free-running mode (used for example by dmix), + // which doesn't update the application pointer. + snd_pcm_uframes_t hw_ptr = runtime->status->hw_ptr; + if (new_hw_ptr == ULONG_MAX) { // initialization + // Usually, this is entered while stopped, before data is queued, + // so both pointers are expected to be zero. + hw_avail = runtime->control->appl_ptr - hw_ptr; + if (hw_avail < 0) + hw_avail += runtime->boundary; + // In free-running mode, appl_ptr will be zero even while running, + // so we end up with a huge number. There is no useful way to + // handle this, so we just clear the whole buffer. + runtime->silence_filled = hw_avail > runtime->buffer_size ? 0 : hw_avail; + runtime->silence_start = hw_ptr; + } else { + snd_pcm_sframes_t played = new_hw_ptr - hw_ptr; + if (played) { + if (played < 0) + played += runtime->boundary; + if (played < runtime->silence_filled) + runtime->silence_filled -= played; + else // This may happen due to a reset. + runtime->silence_filled = 0; + runtime->silence_start = new_hw_ptr; + } + } + frames = runtime->buffer_size - runtime->silence_filled; if (frames <= 0) return; } @@ -425,6 +453,10 @@ 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) @@ -442,10 +474,6 @@ 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 42fe3a4e9154..ecb21697ae3a 100644 --- a/sound/core/pcm_local.h +++ b/sound/core/pcm_local.h @@ -29,7 +29,8 @@ 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); +void snd_pcm_playback_silence(struct snd_pcm_substream *substream, + snd_pcm_uframes_t new_hw_ptr);
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 3d0c4a5b701b..94185267a7b9 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); + snd_pcm_playback_silence(substream, ULONG_MAX); 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); + snd_pcm_playback_silence(substream, ULONG_MAX); 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); + snd_pcm_playback_silence(substream, ULONG_MAX); snd_pcm_stream_unlock_irq(substream); }