[AudioI] Audioinjector Stereo on Radxa Rockpi4(b) - RK3399 Device with Vendor and Mainline Kernel

[Steffen Heilmann]

Hello Guys
i managed to get the wm8731 ai stereo to work with the radxa rk3399 rockpi
4(b).
the steps are basicly the same for the Mainline Kernel and the vendor
version which is 4.4.154.

i´m not a coder or kernel guy. and i don´t say this is the perfect way i
did it. i do not even know everything i changed is necessary.

so perhaps there are some guys out there who will also post their ideas or
help make everything  " how a code should be implemented."

The hardware pinout on the rockpi4 is announced to be the same pinout as
the rpi this is why i choose the device. you can hook up the device without
burning something.

the steps are the nearly the same for both kernel versions. but for
mainline you have to choose the mainline audioinjector code from rpi
source. i also used the armbian dev build environment making
everythin easier.

This is the vendor wiki and the steps describe how to build the vendor
kernel
https://wiki.radxa.com/Rockpi4/dev/kernel-4.4

1- Start with  "Get the kernel source" and clone/ download the source from
github
2- cd to the directory " /arch/arm64/boot/dts/rockchip/overlays-rockpi4/ "
and add
   " audioinjector-wm8731-audio.dtbo \ " as line 16 the the Makefile.
     it  should look like:
*    ...*



*hifiberry-dacplus.dtbo \ audioinjector-wm8731-audio.dtbo \
raspberrypi-7-inch-lcd.dtbo \*
*...*

3- in the same directory add the file
"audioinjector-wm8731-audio-overlay.dts"
  (the attachment i made )
4- in the same directory add the following to the hw_intfc.conf :

*#audioinjector-wm8731-audio on I2C7. Need set:
intfc:i2c7=on#intfc:dtoverlay=audioinjector-wm8731-audio*

5- cd to the directory /sound/soc/rockchip/ an add the following to the
Kconfig file :




*config SND_AUDIOINJECTOR_PI_SOUNDCARD       tristate "Support for
audioinjector.net <http://audioinjector.net> Pi add on soundcard"
 select SND_SOC_WM8731       help           Say Y or M if you want to add
support for audioinjector.net <http://audioinjector.net> Pi Hat*

6-  in the same directory inside the Makefile add to line 36
*snd-soc-audioinjector-pi-soundcard-objs := audioinjector-pi-soundcard.o*
and after the last line add
*obj-$(CONFIG_SND_AUDIOINJECTOR_PI_SOUNDCARD) +=
snd-soc-audioinjector-pi-soundcard.o*

7- to the same directory add this file *audioinjector-pi-soundcard.c * from
attachment (original from raspi source
https://github.com/raspberrypi/linux/blob/rpi-4.19.y/sound/soc/bcm/audioinjector-pi-soundcard.c
)
the changes to audioinjector-pi-soundcard.c file belongs to the i2c code
and to the bclk_ratio inside hw_params
look inside the file i attached and compare with source

8- follow up the vendors guide to build the kernel and to additional steps
with "make menuconfig"

and check settings selected
*Device Drivers -> Sound card support ->  Advanced Linux Sound Architecture
-> ALSA for SoC audio support -> Support for audioinjector.net
<http://audioinjector.net> Pi add on soundcard*

also unselect following because for me did some error while compiling :
*Device Drivers -> Sound card support ->  Advanced Linux Sound Architecture
-> ALSA for SoC audio support ->  CODEC driver -> Rockchip RK3308 CODEC*
and
* Device Drivers -> Sound card support ->  Advanced Linux Sound
Architecture -> ALSA for SoC audio support ->  CODEC driver -> RK3328 CODEC*

 9- for example follow the guide building the *.deb packages and install
them.

10-  booting up should now show the audioinjector stereo device. don´t care
about the errors  as long as u get from dmesg : *audioinjector-stereo
sound-ext-card: wm8731-hifi <-> ff890000.i2s mapping ok*

11- follow https://www.alsa-project.org/wiki/Setting_the_default_device to
select your default device
and reboot again

don´t forget to unmute the device inside alsamixer

Sorry for my bad english and have fun with your audioinjector stereo on
rk3399

Mit freundlichen Grüßen - King regards
*Steffen Heilmann*
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