On 27. 04. 23 7:53, semiydsemiyd@163.com wrote:
Hi
I have 8 alsa capture devices for one card. Each capture device support 1 channel only:
root@light-a-val:~# arecord -l **** List of CAPTURE Hardware Devices **** card 0: LightSoundCard [Light-Sound-Card], device 0: light-tdm-dai-slot1-ES7210 ADC 0 es7210.5-0042-1 [light-tdm-dai-slot1-ES7210 ADC 0 es7210.5-0042-1] Subdevices: 1/8 Subdevice #0: subdevice #0 card 0: LightSoundCard [Light-Sound-Card], device 1: light-tdm-dai-slot2-ES7210 ADC 0 es7210.5-0042-1 [light-tdm-dai-slot1-ES7210 ADC 0 es7210.5-0042-1] Subdevices: 2/8 Subdevice #1: subdevice #1 ... card 0: LightSoundCard [Light-Sound-Card], device 7: light-tdm-dai-slot8-ES7210 ADC 1 es7210.5-0042-1 [light-tdm-dai-slot1-ES7210 ADC 0 es7210.5-0042-1] Subdevices: 8/8 Subdevice #7: subdevice #7
the signal comes in TDM format from external codec ES7210 to my soc's TDM controller. each capture device has 1 channel that correspond to one of the slot in TDM. i have 8 TDM slots in configuration. so i have 8 devices in total.
the reason that i have so many capture devices with 1 channel each is that, our tdm IC design decides that each tdm slot data_register would be assigned a dedicated dma channel. this is quite uncommon. thus i have 8 dma channels for 8 tdm slots. since i can only register one rx dma channel and one tx using devm_snd_dmaengine_pcm_register(). like: struct dmaengine_pcm { struct dma_chan *chan[SNDRV_PCM_STREAM_LAST + 1]; // there can be only one tx + one rx dma for struct dmaengine_pcm ... }; i have to register like 8 times to create 8 devices. the dts for the cpu dai driver for tdm slot1 would look like: tdm: audio_tdm@0xffcb000000 { #sound-dai-cells = <0>; ... dmas = <&dmac2 31>; dma-names = "rx"; ... };
now...i want to open all the devices at the same time. and have them save to one single wav file. As if i'm opening one single alsa capture device with 8 channels. the saved wav file should look something like this (take this 8 channel wav file for example)
You may use the multi plugin from alsa-lib, just google "alsa multi plugin" for details.
Jaroslav