[PATCH v2 1/7] ALSA: pcm: Revert "ALSA: pcm: rewrite snd_pcm_playback_silence()"
From: Jaroslav Kysela perex@perex.cz
This reverts commit 9f656705c5faa18afb26d922cfc64f9fd103c38d.
There was a regression (in the top-up mode). Unfortunately, the patch provided from the author of this commit is not easy to review.
Keep the updated and new comments in headers. Also add a new comment that documents the missed API constraint which led to the regression.
Reported-by: Jeff Chua jeff.chua.linux@gmail.com Link: https://lore.kernel.org/r/CAAJw_ZsbTVd3Es373x_wTNDF7RknGhCD0r+NKUSwAO7HpLAkY... Signed-off-by: Jaroslav Kysela perex@perex.cz Signed-off-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de --- v2: - add docu comment - commit message improvements --- sound/core/pcm_lib.c | 90 ++++++++++++++++++++++++----------------- sound/core/pcm_local.h | 3 +- sound/core/pcm_native.c | 6 +-- 3 files changed, 59 insertions(+), 40 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index d21c73944efd..3357ffae635f 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -42,56 +42,74 @@ 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_uframes_t noise_dist, ofs, transfer; + snd_pcm_uframes_t frames, 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) { - frames = runtime->silence_threshold - noise_dist; - if (frames <= 0) + 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 > runtime->silence_size) frames = runtime->silence_size; } else { - frames = runtime->buffer_size - noise_dist; - if (frames <= 0) - return; + /* + * This filling mode aims at free-running mode (used for example by dmix), + * which doesn't update the application pointer. + */ + 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; } - if (snd_BUG_ON(frames > runtime->buffer_size)) return; - ofs = (runtime->silence_start + runtime->silence_filled) % runtime->buffer_size; - do { + if (frames == 0) + return; + ofs = runtime->silence_start % runtime->buffer_size; + while (frames > 0) { 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); }
@@ -425,6 +443,10 @@ 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 +464,6 @@ 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); }
From: Jaroslav Kysela perex@perex.cz
The snd_pcm_playback_hw_avail() function uses runtime->status->hw_ptr. Unfortunately, in case when we call this function from snd_pcm_update_hw_ptr0(), this variable contains the previous hardware pointer. Use the new_hw_ptr argument to calculate hw_avail (filled samples by the user space) to correct the threshold comparison.
The new_hw_ptr argument may also be set to ULONG_MAX which means the initialization phase. In this case, use runtime->status->hw_ptr.
Suggested-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de Signed-off-by: Jaroslav Kysela perex@perex.cz Reviewed-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de --- sound/core/pcm_lib.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 3357ffae635f..6ad67e7e740c 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -63,7 +63,15 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram } if (runtime->silence_filled >= runtime->buffer_size) return; - noise_dist = snd_pcm_playback_hw_avail(runtime) + runtime->silence_filled; + /* initialization outside pointer updates */ + if (new_hw_ptr == ULONG_MAX) + new_hw_ptr = runtime->status->hw_ptr; + /* get hw_avail with the boundary crossing */ + noise_dist = appl_ptr - new_hw_ptr; + if (noise_dist < 0) + noise_dist += runtime->boundary; + /* total noise distance */ + noise_dist += runtime->silence_filled; if (noise_dist >= (snd_pcm_sframes_t) runtime->silence_threshold) return; frames = runtime->silence_threshold - noise_dist;
From: Jaroslav Kysela perex@perex.cz
Commit 9a826ddba6e ("[ALSA] pcm core: fix silence_start calculations") came with exactly the right commit message, but the patch just made things broken in a different way: We'd fill at a too low address if the area was already partially zeroed, so we'd under-fill. This affected both thresholded mode (where it was somewhat less likely) and top-up mode (where it would be the case consistently).
Co-developed-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de Signed-off-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de Signed-off-by: Jaroslav Kysela perex@perex.cz --- v2: - rewrote commit message - postponed the addition of comments to a subsequent patch where it makes more sense - dropped the part which the subsequent refactoring obsoletes. this reduces the patch to its essentials, making it easier to understand, and reducing churn. --- sound/core/pcm_lib.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 6ad67e7e740c..5ddb74a12030 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -87,29 +87,25 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram 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; + runtime->silence_start = runtime->status->hw_ptr; } 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; } + runtime->silence_start = new_hw_ptr; } frames = runtime->buffer_size - runtime->silence_filled; } if (snd_BUG_ON(frames > runtime->buffer_size)) return; if (frames == 0) return; - ofs = runtime->silence_start % runtime->buffer_size; + ofs = (runtime->silence_start + runtime->silence_filled) % runtime->buffer_size; while (frames > 0) { transfer = ofs + frames > runtime->buffer_size ? runtime->buffer_size - ofs : frames; err = fill_silence_frames(substream, ofs, transfer);
From: Jaroslav Kysela perex@perex.cz
The removed condition handles de facto only one situation where runtime->silence_filled variable is equal to runtime->buffer_size, because this variable cannot go over the buffer size. This case is implicitly caught by the required comparison of the noise distance with the threshold.
Suggested-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de Signed-off-by: Jaroslav Kysela perex@perex.cz Signed-off-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de --- v2: - improved language of commit message --- sound/core/pcm_lib.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 5ddb74a12030..a1838130c830 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -61,8 +61,6 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram runtime->silence_filled = 0; runtime->silence_start = appl_ptr; } - if (runtime->silence_filled >= runtime->buffer_size) - return; /* initialization outside pointer updates */ if (new_hw_ptr == ULONG_MAX) new_hw_ptr = runtime->status->hw_ptr;
From: Jaroslav Kysela perex@perex.cz
The code tracking the added samples in thresholded mode and the code tracking the just played samples in top-up mode are semantically identical, so factor it out to a common function to enhance readability.
Co-developed-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de Signed-off-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de Signed-off-by: Jaroslav Kysela perex@perex.cz --- v2: - nicer function name and variable name - improved language of commit message --- sound/core/pcm_lib.c | 42 ++++++++++++++++++++++-------------------- 1 file changed, 22 insertions(+), 20 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index a1838130c830..670572c9a8cc 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -33,6 +33,25 @@ static int fill_silence_frames(struct snd_pcm_substream *substream, snd_pcm_uframes_t off, snd_pcm_uframes_t frames);
+ +static inline void update_silence_vars(struct snd_pcm_runtime *runtime, + snd_pcm_uframes_t ptr, + snd_pcm_uframes_t new_ptr) +{ + snd_pcm_sframes_t delta; + + delta = new_ptr - ptr; + if (delta == 0) + return; + if (delta < 0) + delta += runtime->boundary; + if ((snd_pcm_uframes_t)delta < runtime->silence_filled) + runtime->silence_filled -= delta; + else + runtime->silence_filled = 0; + runtime->silence_start = new_ptr; +} + /* * fill ring buffer with silence * runtime->silence_start: starting pointer to silence area @@ -49,18 +68,9 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram int err;
if (runtime->silence_size < runtime->boundary) { - snd_pcm_sframes_t noise_dist, n; + snd_pcm_sframes_t noise_dist; 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; - } + update_silence_vars(runtime, runtime->silence_start, appl_ptr); /* initialization outside pointer updates */ if (new_hw_ptr == ULONG_MAX) new_hw_ptr = runtime->status->hw_ptr; @@ -87,15 +97,7 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram runtime->silence_filled = avail > 0 ? avail : 0; runtime->silence_start = runtime->status->hw_ptr; } 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; + update_silence_vars(runtime, runtime->status->hw_ptr, new_hw_ptr); } frames = runtime->buffer_size - runtime->silence_filled; }
Inline the remaining call of snd_pcm_playback_hw_avail(). This makes the top-up branch more congruent with the thresholded one, and allows simplifying the handling of the corner cases.
Signed-off-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de --- sound/core/pcm_lib.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 670572c9a8cc..17fc80a654be 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -90,15 +90,32 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram * This filling mode aims at free-running mode (used for example by dmix), * which doesn't update the application pointer. */ - 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; + snd_pcm_uframes_t hw_ptr = runtime->status->hw_ptr; + if (new_hw_ptr == ULONG_MAX) { + /* + * Initialization, fill the whole unused buffer with silence. + * + * Usually, this is entered while stopped, before data is queued, + * so both pointers are expected to be zero. + */ + snd_pcm_sframes_t avail = runtime->control->appl_ptr - hw_ptr; + if (avail < 0) + 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 = avail > runtime->buffer_size ? 0 : avail; + runtime->silence_start = hw_ptr; } else { - update_silence_vars(runtime, runtime->status->hw_ptr, new_hw_ptr); + /* Silence the just played area immediately */ + update_silence_vars(runtime, hw_ptr, new_hw_ptr); } + /* + * In this mode, silence_filled actually includes the valid + * sample data from the user. + */ frames = runtime->buffer_size - runtime->silence_filled; } if (snd_BUG_ON(frames > runtime->buffer_size))
We already know that `frames` is greater than zero, because we just checked it. So we don't need to check the loop condition on the first iteration.
Signed-off-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de --- sound/core/pcm_lib.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 17fc80a654be..9c121a921b04 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -123,14 +123,14 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram if (frames == 0) return; ofs = (runtime->silence_start + runtime->silence_filled) % runtime->buffer_size; - while (frames > 0) { + 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); }
On Fri, 05 May 2023 17:52:38 +0200, Oswald Buddenhagen wrote:
From: Jaroslav Kysela perex@perex.cz
This reverts commit 9f656705c5faa18afb26d922cfc64f9fd103c38d.
There was a regression (in the top-up mode). Unfortunately, the patch provided from the author of this commit is not easy to review.
Keep the updated and new comments in headers. Also add a new comment that documents the missed API constraint which led to the regression.
Reported-by: Jeff Chua jeff.chua.linux@gmail.com Link: https://lore.kernel.org/r/CAAJw_ZsbTVd3Es373x_wTNDF7RknGhCD0r+NKUSwAO7HpLAkY... Signed-off-by: Jaroslav Kysela perex@perex.cz Signed-off-by: Oswald Buddenhagen oswald.buddenhagen@gmx.de
Applied all 7 patches now. Thanks.
Takashi
participants (2)
-
Oswald Buddenhagen -
Takashi Iwai