alsa device node

alsa device 的列表：

$ cat /proc/asound/devices
 0: [ 0]   : control
 16: [ 0- 0]: digital audio playback
 24: [ 0- 0]: digital audio capture
 32: [ 1]   : control
 33:        : timer
 48: [ 1- 0]: digital audio playback
 56: [ 1- 0]: digital audio capture
 64: [ 2]   : control
 80: [ 2- 0]: digital audio playback
 96: [ 3]   : control
100: [ 3- 0]: hardware dependent
112: [ 3- 0]: digital audio playback
120: [ 3- 0]: digital audio capture

第一行的數字就是 device node 的 minor number


對應到 /dev/snd/ 下：

bash-4.2# ls -l /dev/snd
crw-rw-rw-    1 1000     1005       14,   4 Jan  1  1970 audio
crw-rw-rw-    1 1000     1005       14,  20 Jan  1  1970 audio1
crw-rw-rw-    1 1000     1005       14,  36 Jan  1  1970 audio2
crw-rw-rw-    1 1000     1005       14,  52 Jan  1  1970 audio3
crw-rw-rw-    1 1000     1005      116,   0 Jan  1  1970 controlC0
crw-rw-rw-    1 1000     1005      116,  32 Jan  1  1970 controlC1
crw-rw-rw-    1 1000     1005      116,  64 Jan  1  1970 controlC2
crw-rw-rw-    1 1000     1005      116,  96 Jan  1  1970 controlC3
crw-rw----    1 1000     1005       14,   3 Jan  1  1970 dsp
crw-rw----    1 1000     1005       14,  19 Jan  1  1970 dsp1
crw-rw-rw-    1 1000     1005       14,  35 Jan  1  1970 dsp2
crw-rw-rw-    1 1000     1005       14,  51 Jan  1  1970 dsp3
crw-rw-rw-    1 1000     1005      116, 100 Jan  1  1970 hwC3D0
crw-rw----    1 1000     1005       14,   0 Jan  1  1970 mixer
crw-rw-rw-    1 1000     1005       14,  16 Jan  1  1970 mixer1
crw-rw-rw-    1 1000     1005       14,  32 Jan  1  1970 mixer2
crw-rw-rw-    1 1000     1005       14,  48 Jan  1  1970 mixer3
crw-rw-rw-    1 1000     1005      116,  24 Jan  1  1970 pcmC0D0c
crw-rw-rw-    1 1000     1005      116,  16 Jan  1  1970 pcmC0D0p
crw-rw-rw-    1 1000     1005      116,  56 Jan  1  1970 pcmC1D0c
crw-rw-rw-    1 1000     1005      116,  48 Jan  1  1970 pcmC1D0p
crw-rw-rw-    1 1000     1005      116,  80 Jan  1  1970 pcmC2D0p
crw-rw-rw-    1 1000     1005      116, 120 Jan  1  1970 pcmC3D0c
crw-rw-rw-    1 1000     1005      116, 112 Jan  1  1970 pcmC3D0p
crw-rw-rw-    1 1000     1005      116,  33 Jan  1  1970 timer

可以看到 major, minor number.

對照，

bash-4.2# alsa_aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: ssfinneraudi [SSF internal audio], device 0: SSF internal audio [SSF internal audio]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 1: csrbtcodec [ccs-btcodec], device 0: btcodec hifi btcodec-usppcm-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: ssochdmi [ssoc-hdmi], device 0: HDMI ssoc-hdmi-audio-codec-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 3: ssocrt5625 [ssoc-rt5625], device 0: RT5625 rt5625-aif1-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0