from dmidecode
System Information
Manufacturer: LENOVO
Product Name: 83AA
Version: YogaAir 14s APU8
Wake-up Type: Power Switch
SKU Number: LENOVO_MT_83AA_BU_idea_FM_YogaAir 14s APU8
Family: YogaAir 14s APU8
cat /sys/class/sound/hwC1D0/subsystem_id
0x17aa38bb
It uses TI 2781 for the subwoofer speakers.
The support is in kernel 6.6+. The driver's design has two flaws that makes the runtime PM not work very well.
On each runtime suspend, the driver resets the current program and upon resume it reloads all of the DSP's firmware.
The firmware (/lib/firmware/TIAS2781RCA4.bin) supplied is also flawed as it does hardware resets (instead of software ones) each time the play pauses.
This causes the DSP to shutdown. So on play resume, all the FW (/lib/firmware/TAS2XXX38BB.bin) needs to be uploaded again.
That takes more than 2 secs before the play starts. Even after it starts, it does few pauses.
The easiest solution for this problem is to replace the hardware resets with software ones. That is done by replacing all
occurences of 00 00 5c d9 in the TIAS2781RCA4.bin file with 00 00 5c 19. Check the data sheet for the description of register 5c.
To make the subwoofer's work need the following:
as root (if rc.local doesn't exit - create, make executable and add #!/bin/sh)
cat << EOF >> /etc/rc.local
# Disable runtime suspend/resume for tas 2781 as it is not working
echo on > /sys/bus/i2c/drivers/tas2781-hda/i2c-TIAS2781\:00/power/control
EOF
On Fedora the rc.local file is /etc/rc.d/rc.local
The files TIAS2781RCA4.bin and TAS2XXX38BB.bin need to be copies in /lib/firmware
By default the normal speaker volume controls don't control the volume of the subwoofer's. The 2781 speakers are controlled with a separate control
amixer cget numid=3
numid=3,iface=CARD,name='Speaker Digital Gain'
; type=INTEGER,access=rw---R--,values=1,min=0,max=200,step=0
: values=148
| dBscale-min=-100.00dB,step=1.00dB,mute=0
To make the amp speakers change volume in sync with the volume of the main speakers - use https://github.com/darinpp/alsa-controller It will update the digital gain for the amp speakers when the main speaker's volume changes. The 2781 driver doesn't expose changing the volume of the L/R speakers separately (even though that should work). So changing the L/R balance won't afect the amp speakers.