libgpiod 2 and amixer -c 0 on the mainline board, 2026-10-16

Evidence class: on-board console commands over SSH, typed by hand (not yet the installed script). Board clock: Fri Oct 16 02:56:09 PM UTC 2026. Kernel 7.3.0-rc5 (the mainline DRM shell system), libgpiod v2.2.4.

• /proc/asound/cards lists K230I2SINNO. amixer -c 0 controls includes numid=5,iface=MIXER,name='External I2S Output Switch', and amixer -c 0 cget reads values=off. The mainline kernel carries the route control too.

• amixer controls without -c 0 fails with Control default open error: Host is down, because the default ALSA device is PipeWire’s.

• gpiodetect reports gpiochip1 [9140c000.gpio] (32 lines).

• A libgpiod 2 hold, using the exact form the script now uses:

  gpioset --chip=gpiochip1 --consumer=k230-speaker-test 2=inactive & P=$!
  sleep 0.3; kill -0 $P && echo held        -> held
  gpioinfo -c gpiochip1 2                    -> gpiochip1 2  unnamed  output consumer="k230-speaker-test"
  kill $P; wait $P
  gpioinfo -c gpiochip1 2                    -> gpiochip1 2  unnamed  output
  

  The line is requested and held while gpioset runs and released when it is killed, which is what amp_set/amp_release assume. Only inactive (amp off) was driven; no tone was played.

nix/k230-speaker-test.nix now uses these forms. Task 4.2b closes when the installed k230-speaker-test status prints the control and the line without errors.