atc_prep_slave_sg(9)

💅 atc_prep_slave_sg(9) — your fave Kernel API Manual entry, bestie ✨

okay so picture this: it's the Kernel API Manual, and we're reading atc_prep_slave_sg(9) 💖 no cap, this one is lowkey iconic and it's giving "behind the scenes of a DMA_SLAVE transaction." Let's get into it 🫶

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🎀 NAME 🎀

atc_prep_slave_sg — literally the function that prepares descriptors for a DMA_SLAVE transaction ✨ it's doing the prep work so the actual transfer can slay later, periodt 💅

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🦋 SYNOPSIS 🦋

bestie, here's the signature, exactly as it is, do not come for me about the spacing 😭

struct dma_async_tx_descriptor * atc_prep_slave_sg (struct dma_chan
*chan , struct scatterlist *sgl , unsigned int sg_len , enum
dma_transfer_direction direction , unsigned long flags , void *context
);

it hands you back a struct dma_async_tx_descriptor * and honestly? main character energy 🔥

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🌸 ARGUMENTS 🌸

six little besties walk into the function and here's what each one is about 🧚

• chan — the DMA channel 💫 that's your gal, the one actually doing the thing
• sgl — the scatterlist to transfer to/from 🦋 like, the list of where the data's coming from or going to, whichever way the vibe flows
• sg_len — the number of entries in scatterlist ⭐ so basically how many things are in that list, count 'em
• direction — the DMA direction 🌈 the enum dma_transfer_direction of it all, the way that it tells you which way we're moving
• flags — the tx descriptor status flags 🎀 all the little settings, the seasoning on the descriptor
• context — the transaction context, and bestie please note: it's (ignored) 🙈 not me passing in context just for it to be ignored, we've all been there 😭

genuine heads-up from the original page: context is literally ignored. taking it, not using it. we respect the honesty 💀

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🌟 SEE ALSO 🌟

okay this section is a whole friend group 👑 and the original page says they all live in the kernel file ./drivers/dma/at_hdmac.c — go say hi 💖

• struct atdma_sg(9)
• struct at_desc(9)
• enum atc_status(9)
• struct at_dma_chan(9)
• struct at_dma(9)
• atc_chan_is_enabled(9)
• atc_chan_is_paused(9)
• atc_chan_is_cyclic(9)
• set_lli_eol(9)
• struct at_dma_platform_data(9)
• struct at_dma_slave(9)
• atc_dostart(9)
• atc_calc_bytes_left(9)
• atc_get_llis_residue(9)
• atc_get_residue(9)
• atc_handle_error(9)
• atc_prep_dma_interleaved(9)
• atc_prep_dma_memcpy(9)
• atc_prep_dma_memset(9)
• atc_prep_dma_cyclic(9)
• atc_tx_status(9)
• atc_alloc_chan_resources(9)
• atc_free_chan_resources(9)
• at_dma_off(9)

twenty-four entries, every single one of them accounted for, iykyk 🧚‍♀️✨

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and that's the whole page, bestie 🫶 come back anytime, the kernel lore is always here for you 💜

signed, sealed, delivered: ./drivers/dma, October 2026, atc_prep_slave_sg(9) — mwah 💋🎀