On 25/07/2019 13.22, Peter Ujfalusi wrote:

For DAIs the format size in bits matters when it comes to symmetry. The physical width is the in-memory format size which matters mostly for the platform drivers.

If for example a DAI requests symmetric_samplebits and the first stream is using S24_LE then the second stream would not be allowed to use S24_3LE despite both S24_LE and S24_3LE would need the same clocking on the bus. But S32_LE would be allowed (S24_LE and S32_LE is both physically 32 bits in memory) which would not be compatible with S24_LE on the bus.

Well, this is not correct either as the snd_pcm_hw_constraint_single(substream->runtime, SNDRV_PCM_HW_PARAM_SAMPLE_BITS, soc_dai->sample_bits);

applies to physical width.

After S24_LE stream with this patch only S24_3LE is allowed opposed to S24_LE/S32_LE without it.

I don't see how this can be done correctly.

S24_LE should impose constraint S24_LE | S24_3LE and not allow S32_LE. In theory any format with less than 24bits could be allowed with slot_width = 24, but this might go too far.

- Péter

Signed-off-by: Peter Ujfalusi peter.ujfalusi@ti.com

sound/soc/soc-pcm.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c index 1406f935af22..c70722dc1f4f 100644 --- a/sound/soc/soc-pcm.c +++ b/sound/soc/soc-pcm.c @@ -243,7 +243,7 @@ static int soc_pcm_params_symmetry(struct snd_pcm_substream *substream,

rate = params_rate(params); channels = params_channels(params);

• sample_bits = snd_pcm_format_physical_width(params_format(params));

• sample_bits = snd_pcm_format_width(params_format(params));

  /* reject unmatched parameters when applying symmetry */ symmetry = cpu_dai->driver->symmetric_rates ||

@@ -932,7 +932,7 @@ static int soc_pcm_hw_params(struct snd_pcm_substream *substream,

codec_dai->rate = params_rate(&codec_params);
codec_dai->channels = params_channels(&codec_params);

• codec_dai->sample_bits = snd_pcm_format_physical_width(
  

• codec_dai->sample_bits = snd_pcm_format_width(
  			params_format(&codec_params));
  
  

  snd_soc_dapm_update_dai(substream, &codec_params, codec_dai);

@@ -945,8 +945,7 @@ static int soc_pcm_hw_params(struct snd_pcm_substream *substream, /* store the parameters for each DAIs */ cpu_dai->rate = params_rate(params); cpu_dai->channels = params_channels(params);

• cpu_dai->sample_bits =

• snd_pcm_format_physical_width(params_format(params));
  

• cpu_dai->sample_bits = snd_pcm_format_width(params_format(params));

  snd_soc_dapm_update_dai(substream, params, cpu_dai);

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