Use constraint to make sure the period size could always be multiple
of 1ms to align with the fundamental design/limitation of firmware.
Signed-off-by: Brent Lu <brent...@intel.com>
---
sound/soc/intel/atom/sst-mfld-platform-pcm.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/sound/soc/intel/atom/sst-mfld-platform-pcm.c
b/sound/soc/intel/atom/sst-mfld-platform-pcm.c
index 49b9f18..5f89956 100644
--- a/sound/soc/intel/atom/sst-mfld-platform-pcm.c
+++ b/sound/soc/intel/atom/sst-mfld-platform-pcm.c
@@ -333,6 +333,17 @@ static int sst_media_open(struct snd_pcm_substream
*substream,
if (ret_val < 0)
return ret_val;
+ /*
+ * Make sure the period to be multiple of 1ms to align the
+ * design of firmware. Apply same rule to buffer size to make
+ * sure alsa could always find a value for period size
+ * regardless the buffer size given by user space.
+ */
+ snd_pcm_hw_constraint_step(substream->runtime, 0,
+ SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 48);
+ snd_pcm_hw_constraint_step(substream->runtime, 0,
+ SNDRV_PCM_HW_PARAM_BUFFER_SIZE, 48);
+
/* Make sure, that the period size is always even */
snd_pcm_hw_constraint_step(substream->runtime, 0,
SNDRV_PCM_HW_PARAM_PERIODS, 2);
--
2.7.4
