Issues with plughw working, however raw hw not on MAX98360A

[Dylanger Daly]

Hi all,

I'm currently having issues with my speakers on a Chromebook running the MAX98360A DAC.

director at DRIFTWOOD:~$ aplay -D hw:sc7180rt5682max,1 --dump-hw-params /usr/share/sounds/alsa/Front_Center.wav
XDG_RUNTIME_DIR (/run/user/0) is not owned by us (uid 1000), but by uid 0! (This could e.g. happen if you try to connect to a non-root PulseAudio as a root u)
Playing WAVE '/usr/share/sounds/alsa/Front_Center.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
HW Params of device "hw:sc7180rt5682max,1":
--------------------
ACCESS: MMAP_INTERLEAVED RW_INTERLEAVED
FORMAT: S16_LE
SUBFORMAT: STD
SAMPLE_BITS: 16
FRAME_BITS: 64
CHANNELS: 4
RATE: 48000
PERIOD_TIME: 64000
PERIOD_SIZE: 3072
PERIOD_BYTES: 24576
PERIODS: 2
BUFFER_TIME: 128000
BUFFER_SIZE: 6144
BUFFER_BYTES: 49152
TICK_TIME: ALL
--------------------
aplay: set_params:1358: Channels count non available
director at DRIFTWOOD:~$ aplay -D plughw:sc7180rt5682max,1 --dump-hw-params /usr/share/sounds/alsa/Front_Center.wav
XDG_RUNTIME_DIR (/run/user/0) is not owned by us (uid 1000), but by uid 0! (This could e.g. happen if you try to connect to a non-root PulseAudio as a root u)
Playing WAVE '/usr/share/sounds/alsa/Front_Center.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
HW Params of device "plughw:sc7180rt5682max,1":
--------------------
ACCESS: MMAP_INTERLEAVED MMAP_NONINTERLEAVED MMAP_COMPLEX RW_INTERLEAVED RW_NONINTERLEAVED
FORMAT: S8 U8 S16_LE S16_BE U16_LE U16_BE S24_LE S24_BE U24_LE U24_BE S32_LE S32_BE U32_LE U32_BE FLOAT_LE FLOAT_BE FLOAT64_LE FLOAT64_BE MU_LAW A_LAW IMA_AE
SUBFORMAT: STD
SAMPLE_BITS: [4 64]
FRAME_BITS: [4 640000]
CHANNELS: [1 10000]
RATE: [4000 4294967295)
PERIOD_TIME: 64000
PERIOD_SIZE: [256 274877907)
PERIOD_BYTES: [128 4294967295)
PERIODS: (0 2147484)
BUFFER_TIME: [1 4294967295]
BUFFER_SIZE: [512 549755813]
BUFFER_BYTES: [256 4294967295]
TICK_TIME: ALL
--------------------
When I specify plughw, meaning "add software processing", I can hear perfect output, however if I attempt to use the raw hw handle, I get significantly less format support and the channel count isn't even known, and there is no sound output.

I believe this is happening because the driver isn't being picked up, and plughw simply adds what it can to the device making it work.

The end result is neither PipeWire or PluseAudio detect the speaker device, I assume this is because they're expecting to use the raw hw device handle

Here's my ucm2 config: https://github.com/hexdump0815/imagebuilder/blob/d02a71ace7b93b8efbff8426624458a6668fe680/systems/chromebook_trogdor/extra-files/usr/share/alsa/ucm2/SC7180/HiFi.conf

Any help would be appreciated, thank you