Every time I finish playing through the headphones, I find that the headphone volume is different from the value I originally set. What is the reason for this?
In MTK kernel v5.15, when headset playback stops, the headset volume is decreased from the user-set volume to normal gain step by step, and then set to mute. When using headset playback next time, the headset volume is first set to normal gain, and then increased back to the user-set volume.
In conclusion, it is normal to observe that the headset volume value is not at the user-set value during periods when the headset is not playing.
For example with the Genio-700, this is the status of the headset volume when the headset is not in use.
numid=338,iface=MIXER,name='Headset Volume'
; type=INTEGER,access=rw---R--,values=2,min=0,max=30,step=0
: values=31,31
| dBscale-min=-22.00dB,step=1.00dB,mute=0