Commit d7f5dd97 authored by Jaroslav Kysela's avatar Jaroslav Kysela Committed by Takashi Iwai
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ALSA: pcm: Revert "ALSA: pcm: rewrite snd_pcm_playback_silence()" 



This reverts commit 9f656705.

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: default avatarJeff Chua <jeff.chua.linux@gmail.com>
Link: https://lore.kernel.org/r/CAAJw_ZsbTVd3Es373x_wTNDF7RknGhCD0r+NKUSwAO7HpLAkYA@mail.gmail.com


Signed-off-by: default avatarJaroslav Kysela <perex@perex.cz>
Signed-off-by: default avatarOswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230505155244.2312199-1-oswald.buddenhagen@gmx.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 56fc217f

sound/core/pcm_lib.c

+54 −36
Original line number Diff line number Diff line
@@ -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;

	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;

		}



	// 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)

		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);

sound/core/pcm_local.h

+2 −1
Original line number Diff line number Diff line
@@ -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)

sound/core/pcm_native.c

+3 −3
Original line number Diff line number Diff line
@@ -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);

}