Line-out only works with TRRS cable

Support Linux Support
1

Dear humanity,

I have a BUGZZY board (Samsung Chromebook 2 360) running Arch Linux. This device has a line-out. This line-out only works when connected to a TRRS cable . My JBL Tune 760NC headphones use a TRRS cable, so that is no issue.

Only when connecting to - for example - an amplifier (via RCA → cinch adapter) I can’t get any sound because the adapter doesn’t work with a TRRS cable and my laptop won’t recognize the 3.5mm TRS/TRS cable. When using the same cable with my smartphone, everything works as expected.
Under ChromeOS, it did recognize the TRS cable.
So:

  • When connecting a TRS cable to my BUGZZY Chromebook, the Chromebook won’t detect it.
  • A TRRS cable is detected, but can’t be used in multiple situations.
2

Can you run alsactl monitor and check the output when you plug/unplug both types of cables.

3 
*Plugging in the TRRS cable*
node hw:0, #66 (0,0,0,Headphone Jack,0) VALUE
node hw:0, #67 (0,0,0,Headset Mic Jack,0) VALUE
node hw:0, #61 (2,0,0,Headphone Volume,0) VALUE
*Unplugging the TRRS cable*
node hw:0, #61 (2,0,0,Headphone Volume,0) VALUE
node hw:0, #66 (0,0,0,Headphone Jack,0) VALUE
node hw:0, #67 (0,0,0,Headset Mic Jack,0) VALUE
*Plugging in the TRS cable*
node hw:0, #68 (0,0,0,Line Out Jack,0) VALUE
*Unplugging the TRS cable*
node hw:0, #68 (0,0,0,Line Out Jack,0) VALUE

Interesting indeed, because this indicates that it is recognized by the system, but I can’t select it (tested in pavucontrol, alsamixer, KDE Plasma settings)

4

I’ve never seen a device with a “Line Out Jack” before.

5

Well, here you have one… Under ChromeOS it was also called ‘Line Out’. The output signal is also at line-out level.
Tempering with HDAJackretask does nothing (I’m only able to ‘Install boot overide’ (does nothing), ‘Apply now’ just crashes the whole application.)