Enabling TinyALSA

1. Related Device:

**** List of PLAYBACK Hardware Devices ****
card 0: asoc [mmp3 asoc], device 0: WM8731 wm8731-hifi-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: hdmi [mmp3 hdmi], device 0: hdmi Audio dummy-dai-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

# ll /dev/snd/
drwxr-xr-x  2 root root       80 Jan  1 00:14 by-path/
crw-rw---T  1 root audio 116,  0 Jan  1 00:14 controlC0
crw-rw---T  1 root audio 116, 32 Jan  1 00:14 controlC1
crw-rw---T  1 root audio 116, 24 Jan  1 00:14 pcmC0D0c
crw-rw---T  1 root audio 116, 16 Jan  1 00:14 pcmC0D0p
crw-rw---T  1 root audio 116, 48 Jan  1 00:14 pcmC1D0p
crw-rw---T  1 root audio 116, 33 Jan  1 00:14 timer

2. Supported PCM informations:

# ./tinypcminfo -D 0 -d 0
Info for card 0, device 0:

PCM out:
[64078.792510] mmp_free_dma: trying to free channel 0 which is already freed
        Rate:   min=44100Hz     max=44100Hz
    Channels:   min=2           max=2
 Sample bits:   min=16          max=16
 Period size:   min=8           max=2560
Period count:   min=1           max=256

PCM in:
[64078.815734] mmp_free_dma: trying to free channel 0 which is already freed
        Rate:   min=44100Hz     max=44100Hz
    Channels:   min=1           max=2
 Sample bits:   min=16          max=16
 Period size:   min=8           max=5120
Period count:   min=1           max=256

# ./tinypcminfo -D 1 -d 0                                             
Info for card 1, device 0:

PCM out:
[64180.135162] mmp_free_dma: trying to free channel 0 which is already freed
        Rate:   min=44100Hz     max=44100Hz
    Channels:   min=2           max=2
 Sample bits:   min=16          max=16
 Period size:   min=8           max=2560
Period count:   min=1           max=256

PCM in:
cannot open device '/dev/snd/pcmC1D0c'   // HDMI can't capture
Device does not exist.

3. TinyALSA generated binary results

# ll libtinyalsa.so 
-rwxr-xr-x 1 root root 28072 Jan  1 01:08 libtinyalsa.so*

# ll tinycap
-rwxr-xr-x 1 root root 12976 Jan  1 01:08 tinycap*

# ll tinymix
-rwxr-xr-x 1 root root 13177 Jan  1 01:08 tinymix*

# ll tinypcminfo
-rwxr-xr-x 1 root root 8152 Jan  1 01:08 tinypcminfo*

# ll tinyplay
-rwxr-xr-x 1 root root 13034 Jan  1 01:08 tinyplay*

4. TinyALSA implementation

5. ALSA Driver Implementation and Interaction with wm8731

6. DMA and PCM stream

7. SOC Audio Subsystem