snd_dmaengin...rom_dai_data(9)

💖 NAME 💖

snd_dmaengine_pcm_set_config_from_dai_data — bestie, this one sets up your DMA slave config using the DAI DMA data. Like, it literally initializes a dma slave config from DAI DMA data. That's the whole gig. Periodt.

Welcome to the Kernel API Manual, babes — this page is called snd_dmaengin...rom_dai_data(9) (yes the name got truncated, she's mysterious like that ✨).

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✨ SYNOPSIS ✨

void snd_dmaengine_pcm_set_config_from_dai_data (const struct
    snd_pcm_substream *substream , const struct snd_dmaengine_dai_dma_data
    *dma_data , struct dma_slave_config *slave_config );

No return value, she just does the thing. Void queen 👑.

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🎀 ARGUMENTS 🎀

• substream — the PCM substream. Your main character, honestly.
• dma_data — the DAI DMA data. The vibe source.
• slave_config — the DMA slave configuration. The glow-up target, she's getting filled in.

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🌸 DESCRIPTION 🌸

Okay so here's the tea 🍓: this function initializes the {dst,src}_addr, {dst,src}_maxburst, and {dst,src}_addr_width fields of the DMA slave config — and it pulls them straight from the same fields in the DAI DMA data struct. Copy-paste energy, but make it kernel.

Which fields get set? Depends on the direction of the substream, and she's very intentional about it:

• If the substream is a playback stream → the dst fields get initialized 💅
• If it's a capture stream → the src fields get initialized 🦋

Now, the {dst,src}_addr_width field is a little picky, ngl. It only gets initialized if:

1. the SND_DMAENGINE_PCM_DAI_FLAG_PACK flag is set, or
2. the addr_width field of the DAI DMA data struct is not equal to DMA_SLAVE_BUSWIDTH_UNDEFINED.

And if both of those conditions are met? 👀 The latter takes priority. No cap, that's just the rule. Remember it.

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🔥 SEE ALSO 🔥

The kernel file that's giving source-of-truth, no cap:

• ./sound/core/pcm_dmaengine.c

And the whole friend group 🫶 — go say hi:

• snd_hwparams_to_dma_slave_config(9)
• snd_dmaengine_pcm_trigger(9)
• snd_dmaengine_pcm_pointer_no_residue(9)
• snd_dmaengine_pcm_pointer(9)
• snd_dmaengine_pcm_request_channel(9)
• snd_dmaengine_pcm_open(9)
• snd_dmaengine_pcm_close(9)
• snd_dmaengine_pcm_close_release_chan(9)
• snd_dmaengine_pcm_refine_runtime_hwparams(9)

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Okay bye bestie, go configure those DMA slaves 💜✨ This page lives in ./sound/core, dated October 2026, and it's brought to you by the Kernel API Manual — slay, read responsibly, and remember: the dst fields are for playback, the src fields are for capture, and DMA_SLAVE_BUSWIDTH_UNDEFINED is not the vibe. 🎀👑