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-rw-r--r--sound/soc/sof/intel/hda-pcm.c29
1 files changed, 29 insertions, 0 deletions
diff --git a/sound/soc/sof/intel/hda-pcm.c b/sound/soc/sof/intel/hda-pcm.c
index 18f07364d2..d7b446f3f9 100644
--- a/sound/soc/sof/intel/hda-pcm.c
+++ b/sound/soc/sof/intel/hda-pcm.c
@@ -259,8 +259,37 @@ int hda_dsp_pcm_open(struct snd_sof_dev *sdev,
snd_pcm_hw_constraint_mask64(substream->runtime, SNDRV_PCM_HW_PARAM_FORMAT,
SNDRV_PCM_FMTBIT_S16 | SNDRV_PCM_FMTBIT_S32);
+ /*
+ * The dsp_max_burst_size_in_ms is the length of the maximum burst size
+ * of the host DMA in the ALSA buffer.
+ *
+ * On playback start the DMA will transfer dsp_max_burst_size_in_ms
+ * amount of data in one initial burst to fill up the host DMA buffer.
+ * Consequent DMA burst sizes are shorter and their length can vary.
+ * To make sure that userspace allocate large enough ALSA buffer we need
+ * to place a constraint on the buffer time.
+ *
+ * On capture the DMA will transfer 1ms chunks.
+ *
+ * Exact dsp_max_burst_size_in_ms constraint is racy, so set the
+ * constraint to a minimum of 2x dsp_max_burst_size_in_ms.
+ */
+ if (spcm->stream[direction].dsp_max_burst_size_in_ms)
+ snd_pcm_hw_constraint_minmax(substream->runtime,
+ SNDRV_PCM_HW_PARAM_BUFFER_TIME,
+ spcm->stream[direction].dsp_max_burst_size_in_ms * USEC_PER_MSEC * 2,
+ UINT_MAX);
+
/* binding pcm substream to hda stream */
substream->runtime->private_data = &dsp_stream->hstream;
+
+ /*
+ * Reset the llp cache values (they are used for LLP compensation in
+ * case the counter is not reset)
+ */
+ dsp_stream->pplcllpl = 0;
+ dsp_stream->pplcllpu = 0;
+
return 0;
}