[PATCH 14/14] ASoC: SOF: Intel: hda-dai: protect hw_params against successive calls

[Pierre-Louis Bossart]

Once we've set-up the HDA stream and its format, we currently don't
support additional format changes. We already have a protection in the
.prepare case, but this needs to be added in the hw_params too.

In mixing use cases where two DPCM FEs are connected to the same BE,
if can happen that there are multiple calls to the BE hw_params when
the two FEs are configured simultaneously.

This could alternatively be fixed at the DPCM level but that's a more
intrusive change requiring infrastructure changes: this would need to
be paired with the definition of fixed hw_params at the mixer level.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
Reviewed-by: Rander Wang <rander.wang at intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi at linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao at linux.intel.com>
---
 sound/soc/sof/intel/hda-dai.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sound/soc/sof/intel/hda-dai.c b/sound/soc/sof/intel/hda-dai.c
index 53600c6c29116..9823230d2ef4a 100644
--- a/sound/soc/sof/intel/hda-dai.c
+++ b/sound/soc/sof/intel/hda-dai.c
@@ -336,8 +336,13 @@ static int hda_dai_hw_params(struct snd_pcm_substream *substream,
 			     struct snd_pcm_hw_params *params,
 			     struct snd_soc_dai *dai)
 {
+	struct hdac_ext_stream *hext_stream =
+				snd_soc_dai_get_dma_data(dai, substream);
 	int ret;
 
+	if (hext_stream && hext_stream->link_prepared)
+		return 0;
+
 	ret = hda_link_dma_hw_params(substream, params);
 	if (ret < 0)
 		return ret;
-- 
2.30.2