Reporting here as instructed in https://bugs.freedesktop.org/show_bug.cgi?id=90972#c16 which also contains alsa-info output etc. I don't really know what it is I'm reporting, but I'm hoping the instruction I got warrants it. I'll happily provide more information if given instructions on how to obtain it.
when loopback mixing mode is enabled, both headphone and internal speaker are connectef to node 0x13 audio output which has speaker+lo playback volume through node 0x1c =audio selector and node 0x1b audio mixer this mean that headphone playack volume control does not affect headphone any more especially speaker+lo playback volume are turn off by pulseaudio , headphone does not get any signal from DAC Node 0x0b [Pin Complex] wcaps 0x400581: Stereo Control: name="Headphone Jack", index=0, device=0 Pincap 0x0001001c: OUT HP EAPD Detect EAPD 0x2: EAPD Pin Default 0x0421101f: [Jack] HP Out at Ext Right Conn = 1/8, Color = Black DefAssociation = 0x1, Sequence = 0xf Pin-ctls: 0xc0: OUT HP Unsolicited: tag=01, enabled=1 Power states: Power: setting=D0, actual=D0 Connection: 3 0x13 0x14 0x1c* Node 0x0d [Pin Complex] wcaps 0x400501: Stereo Control: name="Speaker Phantom Jack", index=0, device=0 Pincap 0x00010050: OUT EAPD Balanced EAPD 0x2: EAPD Pin Default 0x90170110: [Fixed] Speaker at Int N/A Conn = Analog, Color = Unknown DefAssociation = 0x1, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x00: Power states: Power: setting=D0, actual=D0 Connection: 3 0x13 0x14 0x1c* Node 0x13 [Audio Output] wcaps 0xd0c45: Stereo Amp-Out R/L Control: name="Speaker+LO Playback Volume", index=0, device=0 ControlAmp: chs=3, dir=Out, idx=0, ofs=0 Control: name="Speaker+LO Playback Switch", index=0, device=0 ControlAmp: chs=3, dir=Out, idx=0, ofs=0 Device: name="92HD81B1X5 Analog", type="Audio", device=0 Amp-Out caps: N/A Amp-Out vals: [0x80 0x80] Converter: stream=8, channel=0 Power states: Power: setting=D0, actual=D0 Delay: 13 samples Processing caps: benign=0, ncoeff=0 Node 0x14 [Audio Output] wcaps 0xd0c45: Stereo Amp-Out R/L Control: name="Headphone Playback Volume", index=0, device=0 ControlAmp: chs=3, dir=Out, idx=0, ofs=0 Control: name="Headphone Playback Switch", index=0, device=0 ControlAmp: chs=3, dir=Out, idx=0, ofs=0 Amp-Out caps: N/A Amp-Out vals: [0x5f 0x5f] Converter: stream=8, channel=0 Power states: Power: setting=D3, actual=D3 Delay: 13 samples Processing caps: benign=0, ncoeff=0 Node 0x1b [Audio Mixer] wcaps 0x20050b: Stereo Amp-In Control: name="Mic Playback Volume", index=0, device=0 ControlAmp: chs=3, dir=In, idx=0, ofs=0 Control: name="Mic Playback Switch", index=0, device=0 ControlAmp: chs=3, dir=In, idx=0, ofs=0 Control: name="Line Playback Volume", index=0, device=0 ControlAmp: chs=3, dir=In, idx=2, ofs=0 Control: name="Line Playback Switch", index=0, device=0 ControlAmp: chs=3, dir=In, idx=2, ofs=0 Amp-In caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1 Amp-In vals: [0x80 0x80] [0x80 0x80] [0x80 0x80] [0x17 0x17] [0x80 0x80] [0x80 0x80] Power states: Power: setting=D0, actual=D0 Connection: 6 0x0c 0x0e 0x0f 0x13 0x14 0x0a Node 0x1c [Audio Selector] wcaps 0x30050d: Stereo Amp-Out Amp-Out caps: ofs=0x1f, nsteps=0x1f, stepsize=0x05, mute=1 Amp-Out vals: [0x1f 0x1f] Power states: Power: setting=D0, actual=D0 Connection: 1 0x1b
This is the designed behavior. Only the primary path is used intentionally for aamix path.
https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/tree/Documentation/sound/alsa/HD-Audio-Controls.txt if it is the designed behaviour , it should be document realtek codec don't have this behaviour since the aa mixer does not have any DAC input and aamixer can connect to all output jacks the alternative solution is pulseaudio alway disable loopback mixing in analog-output.conf.common
but desktop user need line playback volume and mic playback this mean pulseaudio need to distinguish notebook and desktop