snd_pcm_add_chmap_ctls(9)

📦 version 7.3.1, in nixpkgs unstable

💖 snd_pcm_add_chmap_ctls — a kernel API manual moment ✨

okay so bestie, welcome to the Kernel API Manual page for snd_pcm_add_chmap_ctls(9). pull up a chair, grab a lil snack 🍓, and let's get into it — this one's all about making channel-mapping control elements. yes. literally that. 💅

🌸 NAME 🌸

snd_pcm_add_chmap_ctls — create channel-mapping control elements 🎀

✨ SYNOPSIS ✨

int snd_pcm_add_chmap_ctls (struct snd_pcm *pcm , int stream , const
       struct snd_pcm_chmap_elem *chmap , int max_channels , unsigned long
       private_value , struct snd_pcm_chmap **info_ret );

that's the whole signature, no cap — don't be scared of it, we're gonna walk through every single piece 🫶

🎀 ARGUMENTS 🎀

  • pcm — the assigned PCM instance. like, the PCM you're attaching all this to 💖
  • stream — stream direction 👑
  • chmap — channel map elements (for query). it's the const struct snd_pcm_chmap_elem *, the lookup squad 🔍
  • max_channels — the max number of channels for the stream. yes, the max. not the min, not the vibe, the max 🌈
  • private_value — the value passed to each kcontrol's private_value field. it literally goes straight in there, that's the whole job 🫡
  • info_ret — store struct snd_pcm_chmap instance if non-NULL. so if you hand it a real pointer, it'll tuck the instance in there for you 🧚

💅 DESCRIPTION 💅

Create channel-mapping control elements assigned to the given PCM stream(s). that's it, that's the whole bit — it's giving "do one thing and do it iconically." ✨

like honestly? this is the function you call when you want your PCM stream to have chmap controls and you want the kernel to handle the setup. slay. 🔥

⭐ RETURN ⭐

Zero if successful, or a negative error value. so: 0 = we ate 💖, negative = something went sideways 😭. check it, always check it, fr fr.

🦋 SEE ALSO 🦋

Kernel file ./sound/core/pcm_lib.c — go read it, iykyk 📖, and while you're at it, the whole friend group:

all thirty of them, none skipped, we do not ghost our references 💜

lowkey reminder bestie: info_ret only gets filled in when it's non-NULL. that's not me being dramatic, that's just the spec 🙈

okay that's the page!! 🌸 this lil gem lives in ./sound/core and the version/date stamp on it is October 2026 — so yeah, future-coded but make it kernel. signing off, ily, go read pcm_lib.c 🧚💖🎀

📦 where this page comes from