ASoC: SOF: Intel: hda-pcm: Use dsp_max_burst_size_in_ms to place constraint

If the PCM have the dsp_max_burst_size_in_ms set then place a constraint
to limit the minimum buffer time to avoid xruns caused by DMA bursts
spinning on the ALSA buffer.

Cc: stable@vger.kernel.org # 6.8
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://msgid.link/r/20240321130814.4412-4-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/sof/intel/hda-pcm.c b/sound/soc/sof/intel/hda-pcm.c
index 18f07364d2198425bffd3e111a546e11b536cd63..69fefcd1abc5b481543bcc59a823b56cd27b2250 100644 (file)
--- a/sound/soc/sof/intel/hda-pcm.c
+++ b/sound/soc/sof/intel/hda-pcm.c
@@ -259,6 +259,27 @@ 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;
        return 0;