On 2017年06月06日 16:04, Kuninori Morimoto wrote:
Furthermore, PCM runtime require constraints for channels and rates. In ALSA SoC part, this is done by 'soc_pcm_init_runtime_hw()' in 'sound/soc/soc-pcm.c'. Your driver should have proper values in data of 'struct snd_soc_pcm_stream' as the constraints.
(struct snd_soc_dai_driver.playback or capture?) struct snd_soc_pcm_stream.channels_min = 2 struct snd_soc_pcm_stream.channels_max = 8 struct snd_soc_pcm_stream.rate_min = 48000 struct snd_soc_pcm_stream.rate_max = 192000 struct snd_soc_pcm_stream.rates = SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_192000Here, I'm not yet 100% understanding about these value. I think, above are constraints of whole driver (= it supports both 2ch, 8ch).
It's not my intension. I don't know exactly where you implement 'struct snd_soc_pcm_stream' data in your driver. Perhaps as a part of 'struct snd_soc_dai_driver' data.
About rate_min/max and rates. is this "rate_min" 48000 (= maximum rate of min case = 8ch) ?? not 8000 ? (For example, if 2ch supports 8000-192000, 8ch supports 8000-48000)
And is .rates "SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_192000" ? not SNDRV_PCM_RATE_8000_192000 ?
In my code snippets, I assumed that the hardware supports just two modes; 8ch/48.0kHz and 2ch/192.0kHz. You can expand the snippets as your case. Even if using SNDRV_PCM_RATE_8000_192000, role of the 'hw_rule_rate()' and the 'hw_rule_channels()' is invariant. The former checks channels parameters and constrains rate parameter with valid interval. The latter checks and constraints vice versa with valid list.
Regards
Takashi Sakamoto