fsl_dma_pointer(9)

📦 version 7.3.1, in nixpkgs unstable

💅 fsl_dma_pointer(9) — the kernel API manual, bestie edition 🎀

okay so real talk, this page is from the kernel API manual, and it's literally about fsl_dma_pointer — one tiny function that answers the biggest question in audio streaming: where are we right now? 👀✨

✨ NAME ✨

fsl_dma_pointer — determine the current position of the DMA transfer 🎯

🦋 SYNOPSIS 🦋

snd_pcm_uframes_t fsl_dma_pointer (struct snd_soc_component *component ,
struct snd_pcm_substream *substream );

that's the whole signature, no cap. two args, one snd_pcm_uframes_t back. she's compact, she's iconic 💅

🌸 ARGUMENTS 🌸

  • component — -- undescribed -- 🙈 so the manpage itself literally has nothing to say about it here. ngl, she's giving mystery. we don't invent details, so we just pass it along as-is, fr fr.
  • substream — -- undescribed -- same energy 😭 also undescribed in the original. not me reading the source to figure it out — that's a you activity, bestie.

💖 DESCRIPTION 💖

so this function? ALSA calls it when ALSA wants to know where in the stream buffer the hardware currently is. that's the whole job. it's the "where u at" text of kernel audio 🫶

here's the breakdown, and you're gonna eat this up:

  • for playback, the SAR register contains the physical address of the most recent DMA transfer. like, that's the receipts of the last move 📍
  • for capture, the value lives in the DAR register instead. different register, same vibe 🎀
  • the base address of the buffer is stored in the source_addr field of the first link descriptor. so pointer = current spot minus that base. iykyk 💫

⭐ SEE ALSO ⭐

that's ten references, bestie — read the whole clique 😌👑

and that's the page!! 🌈 this one's filed under ./sound/soc/fsl, stamped October 2026, and it's fsl_dma_pointer(9) all the way down. go hydrate and go read the source 💜🍓✨

📦 where this page comes from