Re: [PATCH] ASoC: qcom: q6asm: Correct the 24-bit capture format

[Demeter Barna]

On 2026-11-01 19:05, Michael McAllister wrote:
> Recording in S24_LE on my Moto G10 produces badly scaled samples that
> wrap at full scale. The PCM V2 DSP interface places 24-bit samples in
> bits 31:8 of each 32-bit word, but ALSA S24_LE expects bits 23:0.

I see the same on SM8350 with v7.4-rc1. Without the patch, S24_LE
recordings from the DMICs wrap at full scale, while the actual signal
sits in the upper 24 bits. With it, capture offers S32_LE with 24
significant bits, the recording matches the S16_LE one, and both
PipeWire and plughw work.

Playback has the same problem: the DSP also takes 24-bit samples from
the upper 24 bits, so S24_LE playback comes out barely audible. Offering
S32_LE with 24 significant bits for playback as well brings it to the
expected level. I suspect this has gone unnoticed because userspace
hides it: distributions for these devices tend to force S16LE in their
PipeWire configuration to work around quiet audio.

Would you like to cover playback in a v2, or should I send a playback
patch on top of yours?

Tested-by: Demeter Barna <me@xxxxxxxxxxxxxxxxxxx> # SM8350