Either toggling 0x0030 bits 3 (DAC_POWERUP) and 4 (HEADPHONE_POWERUP) or 14 (DAC_MONO, which selects MONO or STEREO mode) popping sounds show up at each writing. They seem related to the abrupt powering-up/down of the codec’s DAC.
To power up and down DAC and headphone amplifier toggling DAC_POWERUP and HEADPHONE_POWERUP bits:
Is it possible to implement a software solution to the problem in the sgtl5000 driver that would avoid the powerups and the mono / stereo switch, so that the audio pops are avoided?
It looks like audio is not working on the mainline image:
root@apalis-tk1-mainline:~# grep Mainline /etc/issue
Apalis-TK1-Mainline_LXDE-Image 2.8b5.156 20181228
root@apalis-tk1-mainline:~# aplay /usr/share/sounds/alsa/Front_Center.wav
aplay: main:807: audio open error: No such file or directory
root@apalis-tk1-mainline:~# aplay --device hw:1,0 --rate 48000 --channels 2 --format S16_LE /usr/share/sounds/alsa/Front_Center.wav
Playing WAVE '/usr/share/sounds/alsa/Front_Center.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
aplay: set_params:1324: Channels count non available
Anyway using mainline kernel is not an option for us.
we integrated the first three patches in our system (Ixora v1.1 carrier board and Toradex Linux BSP 2.8b5), those published on 2019-04-26, and the pop sound disappeared when playing any audio file.