Analog audio on Lime2 with stable kernel (version 4.9)

[Fex]

While analog audio output (through the GPIO connector) works out of the box using the legacy kernel 3.4.113-sun7i, I could not get it to work with the stable kernel 4.9.12-sunxi.

 

Since the driver is not activated in the stable kernel, I added the following to the dts:

&codec {
	status = "okay";
};

This lead to the following `dmesg` output:

sun4i-codec 1c22c00.codec: Codec <-> 1c22c00.codec mapping ok

`aplay -l` gives:

**** List of PLAYBACK Hardware Devices ****
card 0: sun4icodec [sun4i-codec], device 0: CDC PCM Codec-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

However when I play back some audio file, no sound is generated. Also using the legacy kernel, there is a particular point during boot time, when the power line hum goes away. In the stable kernel this does not happen; the hum stays.

 

Does anybody know to fix this?

[Fex]

I found the solution: Unmute "Power Amplifier DAC" and "Power Amplifier Mute". Why those are muted per default is beyond me :-)

See http://linux-sunxi.org/Audio_Codec