ASoC: SOF: ipc4-topology: Change DeepBuffer from static to dynamic mode by ujfalusi · Pull Request #5673 · thesofproject/linux

ujfalusi · 2026-02-19T09:41:16Z

Currently the DeepBuffer results static host DMA buffer and thus static
minimum ALSA period size which can be a limiting factor for user space.
DeepBuffer of static 100ms host DMA buffer can only be opened with at least
110ms ALSA period size, if for the same endpoint there is a need for
smaller (or larger) buffer then a new PCM device must be created with
different DeepBuffer configuration.
This does not scale in real life.

With Dynamic DeepBuffer the host DAM buffer size is calculated based on the
requested ALSA period size (with a headroom between the two) using the
DEEP_BUFFER token as a maximum limit for the host DMA buffer.
This way applications can use the same DeepBuffer enabled PCM for different
use cases and still benefit of the power saving of a bigger host DMA
buffer.
As an example, the DEEP_BUFFER in topology is set to 100ms (interpreted as
maximum size with this patch):
ALSA period time of 20ms will result 10ms host DMA Buffer
 - before the patch if 10ms host DMA buffer was desired, the minimum ALSA
   period size was 20ms
ALSA period size of 50ms will result 40ms host DMA buffer
 - before the patch if 40ms host DMA buffer was desired, the minimum ALSA
   period size was 50ms
ALSA period size of 110ms will result 100ms host DMA buffer
 - before the patch if 100ms host DMA buffer was desired, the minimum ALSA
   period size was 110ms
ALSA period size of 500ms will result 100ms host DMA buffer
 - Like before this patch: 500ms ALSA period would use 100ms host DMA
   buffer

The Dynamic DeepBuffer will give applications the means to choose between
lower latency (small host DMA buffer) or higher power save (big host DMA
buffer) with higher latency on the same device with topology providing a
meaningful upper limit of the buffer size.

Currently the DeepBuffer results static host DMA buffer and thus static minimum ALSA period size which can be a limiting factor for user space. DeepBuffer of static 100ms host DMA buffer can only be opened with at least 110ms ALSA period size, if for the same endpoint there is a need for smaller (or larger) buffer then a new PCM device must be created with different DeepBuffer configuration. This does not scale in real life. With Dynamic DeepBuffer the host DAM buffer size is calculated based on the requested ALSA period size (with a headroom between the two) using the DEEP_BUFFER token as a maximum limit for the host DMA buffer. This way applications can use the same DeepBuffer enabled PCM for different use cases and still benefit of the power saving of a bigger host DMA buffer. As an example, the DEEP_BUFFER in topology is set to 100ms (interpreted as maximum size with this patch): ALSA period time of 20ms will result 10ms host DMA Buffer - before the patch if 10ms host DMA buffer was desired, the minimum ALSA period size was 20ms ALSA period size of 50ms will result 40ms host DMA buffer - before the patch if 40ms host DMA buffer was desired, the minimum ALSA period size was 50ms ALSA period size of 110ms will result 100ms host DMA buffer - before the patch if 100ms host DMA buffer was desired, the minimum ALSA period size was 110ms ALSA period size of 500ms will result 100ms host DMA buffer - Like before this patch: 500ms ALSA period would use 100ms host DMA buffer The Dynamic DeepBuffer will give applications the means to choose between lower latency (small host DMA buffer) or higher power save (big host DMA buffer) with higher latency on the same device with topology providing a meaningful upper limit of the buffer size. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>

…st_size_in_ms The meaning of the variable has changed with he Dynamic DeepBuffer and it reflects the smallest burst that the host DMA does. This can be used to set the minimum period time constraint to avoid overshooting by the DMA burst. Change the name and update the related code in Intel hda_dsp_pcm_open() to reflect the revised meaning. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>

lgirdwood · 2026-02-19T09:46:14Z

@naveen-manohar @udaymb pls review.

lgirdwood

LGTM @ujfalusi I assume the rule applies to both directions and works well with latency/position reporting granularity ? i.e. we dont need to update the granularity of position reporting coming from FW/driver ?

ujfalusi · 2026-02-19T10:31:24Z

LGTM @ujfalusi I assume the rule applies to both directions and works well with latency/position reporting granularity ? i.e. we dont need to update the granularity of position reporting coming from FW/driver ?

The position and delay reporting is not affected by the change, everything works as it used to work.

With Dynamic DeepBuffer the host DMA buffer size is calculated based on the requested ALSA period size (with a headroom between the two) using the DEEP_BUFFER token as a maximum limit for the host DMA buffer. This way applications can use the same DeepBuffer enabled PCM for different use cases and still benefit of the power saving of a bigger host DMA Kernel has been updated thesofproject/linux#5673 Signed-off-by: Uday M Bhat <uday.m.bhat@intel.com>

lyakh · 2026-02-20T07:57:42Z

sound/soc/sof/ipc4-topology.c

+			"Failed to parse deep buffer dma size for %s\n",
+			swidget->widget->name);
+		buffer_bytes = min_size;
+		goto out;


not just return min_size;?

no, we want to print the dma buffer configuration.

lyakh · 2026-02-20T08:00:27Z

sound/soc/sof/ipc4-topology.c

+	if (deep_buffer_dma_ms)
+		dev_dbg(scomp->dev,
+			"%s, dma buffer%s: %u ms (max: %u) / %u bytes, ALSA period: %u / %u\n",
+			swidget->widget->name, deep_buffer_dma_ms ? " (using Deep Buffer)" : "",


you already know, that deep_buffer_dma_ms != 0

yes, just occurred to me as well ;)
but the string is already too long :(

lyakh · 2026-02-20T08:09:01Z

sound/soc/sof/intel/hda-pcm.c

 			SNDRV_PCM_HW_PARAM_PERIOD_TIME,
-			period_time * USEC_PER_MSEC,
+			spcm->stream[direction].dsp_min_burst_size_in_ms * USEC_PER_MSEC,
 			UINT_MAX);


just to double check - this is correct - using a "min" value to set a "max" constraint?

using the min value to set the min constraint, max is UINT_MAX, This is why I'm renaming the variable.

ujfalusi added 2 commits February 19, 2026 11:38

ujfalusi requested review from naveen-manohar, singalsu and udaymb February 19, 2026 09:41

ujfalusi requested review from bardliao, dbaluta, kv2019i, lgirdwood, lyakh, plbossart and ranj063 as code owners February 19, 2026 09:41

lgirdwood reviewed Feb 19, 2026

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ujfalusi mentioned this pull request Feb 19, 2026

ASoC: SOF: Initial support for IPC4 compress offload #5647

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udaymb mentioned this pull request Feb 20, 2026

topology2: tplg-targets-sdca-generic: remove 10ms deep buffer dma buffer thesofproject/sof#10559

Open

lyakh reviewed Feb 20, 2026

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ujfalusi mentioned this pull request Feb 20, 2026

topology2: add support form compressed playback thesofproject/sof#10547

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ASoC: SOF: ipc4-topology: Change DeepBuffer from static to dynamic mode#5673

ASoC: SOF: ipc4-topology: Change DeepBuffer from static to dynamic mode#5673
ujfalusi wants to merge 2 commits intothesofproject:topic/sof-devfrom
ujfalusi:peter/sof/pr/dynamic_deepbuffer_ipc4

ujfalusi commented Feb 19, 2026

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