HDAudio implementation found in sound/pci/hda expects a valid stream pointer in substream->runtime->private_data location. For ASoC users, that should point to a valid link stream which is assigned when BE opens.

As BE borrows its runtime from FE, the information may be lost when reparenting comes into picture - see dpcm_be_reparent(). To support the DPCM reparenting functionality for HDAudio scenarios while still fulfilling expectations of HDAudio common code, have all FEs point to the same private data.

Signed-off-by: Cezary Rojewski cezary.rojewski@intel.com ---

This is a tough one and spawned a range of patches. Some of the discussion is present at thesofproject/linux [1]. In the end decided to drop any soc-core/pcm.c modifications for now, instead addressing the problem directly in the avs-driver. Long term - perhaps BE should have a separate runtime so there is no ambiguity between FE and BE.

[1]: https://github.com/thesofproject/linux/pull/3987

sound/soc/intel/avs/pcm.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/sound/soc/intel/avs/pcm.c b/sound/soc/intel/avs/pcm.c index e237ab23fef9..41030aaae02d 100644 --- a/sound/soc/intel/avs/pcm.c +++ b/sound/soc/intel/avs/pcm.c @@ -1507,9 +1507,29 @@ static int avs_component_hda_open(struct snd_soc_component *component,

if (!rtd->dai_link->no_pcm) { struct snd_pcm_hardware hwparams = avs_pcm_hardware; + struct snd_soc_pcm_runtime *be; + struct snd_soc_dpcm *dpcm; + int dir = substream->stream; + + /* + * Support the DPCM reparenting while still fulfilling expectations of HDAudio + * common code - a valid stream pointer at substream->runtime->private_data - + * by having all FEs point to the same private data. + */ + for_each_dpcm_be(rtd, dir, dpcm) { + struct snd_pcm_substream *be_substream; + + be = dpcm->be; + if (be->dpcm[dir].users == 1) + break; + + be_substream = snd_soc_dpcm_get_substream(be, dir); + substream->runtime->private_data = be_substream->runtime->private_data; + break; + }

/* RESUME unsupported for de-coupled HD-Audio capture. */ - if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) + if (dir == SNDRV_PCM_STREAM_CAPTURE) hwparams.info &= ~SNDRV_PCM_INFO_RESUME;

return snd_soc_set_runtime_hwparams(substream, &hwparams);