stm32mp156C-DK2: amixer sound configuration "invalid argument"

[AVazquez]

Hi all!

I am testing the audio configuration for the stm32mp156C-Dk2, with lastest demo(4.0.1-openstlinux-5.15-yocto-kirkstone-mp1-v22.06.15).

I followed the sound card configuration [tutorial](https://wiki.st.com/stm32mpu/wiki/Soundcard_configuration) and I can't configurate correctly somes controls.

E.g (Analog Playback Volume)

root@stm32mp1:~# amixer -c STM32MP15DK cset name='Analog Playback Volume' '204','204'
amixer: Control sysdefault:0 element write error: Invalid argument
 
root@stm32mp1:~# amixer -c STM32MP15DK cset name='Analog Playback Volume' '100','100'
numid=3,iface=MIXER,name='Analog Playback Volume'
 ; type=INTEGER,access=rw---R--,values=2,min=0,max=228,step=0
 : values=100,100
 | dBscale-min=-102.00dB,step=0.50dB,mute=0

In this case, the max argument is 228 but when I try it with the value 204, it says: "invalid argument" but with other lower value it works...

This also happen with others controls.

What is the reason for this to happen?

Regards!

Thanks!

[Grodriguez]

This is actually a bug that was introduced in the upstream kernel, in commit 4f1e50d6a9cf9c1b8c859d449b5031cacfa8404e ("ASoC: ops: Reject out of bounds values in snd_soc_put_volsw_sx()"). The problem is described in this thread: https://lore.kernel.org/all/[e-mail]/T/

The following patch should fix it:

https://lore.kernel.org/all/[e-mail]/

Note, that patch series also has an additional patch to apply bounds checking to the second channel:

https://lore.kernel.org/all/[e-mail]/

That 2nd channel patch is broken; if you apply it, make sure to also apply this fix:

https://lore.kernel.org/all/[e-mail]/

Guillermo

[AVazquez]

Thanks @Grodriguez​ , this solves the problem completely.

I hope they will integrate these patches in a future release.

Cheers.

Alejandro.

[Grodriguez]

Additionally, if your kernel has this patch applied:

https://lore.kernel.org/all/[e-mail]/

This is wrong and breaks the volume range for the "PGA Volume" control. The following patch reverts this:

https://lore.kernel.org/all/[e-mail]/

Full discussion here:

https://lore.kernel.org/all/[e-mail]/

Guillermo