atc_prep_dma_cyclic(9)

💅 atc_prep_dma_cyclic — Kernel API Manual ✨

okay so bestie, this is the one that prepares a cyclic DMA transfer — like, the DMA goes round and round forever, no cap. It's an iconic little function and honestly it's giving main character energy in ./drivers/dma/at_hdmac.c. 🦋

🌸 SYNOPSIS 🌸

struct dma_async_tx_descriptor * atc_prep_dma_cyclic (struct dma_chan
*chan , dma_addr_t buf_addr , size_t buf_len , size_t period_len , enum
dma_transfer_direction direction , unsigned long flags );

like, yes, that's the whole signature, copy it exactly bestie, don't be weird about it 💖

🎀 ARGUMENTS 🎀

• chan — the DMA channel you're prepping. this is your channel, the one you're setting up. 🫶
• buf_addr — the physical DMA address where the buffer starts. physical, bestie, not the virtual one, ok? 😭
• buf_len — total number of bytes for the entire buffer. the whole thing. periodt. ✨
• period_len — number of bytes for each period. so like, the buffer gets chopped into periods of this size, iykyk. 🎀
• direction — transfer direction, to or from device. lowkey self-explanatory but we said it anyway 💅
• flags — tx descriptor status flags. the flags go here. yes, those flags. ⭐

👑 SEE ALSO 👑

k so the source file is ./drivers/dma/at_hdmac.c and honestly there's a whole friend group hanging out with this function, go say hi to all of them:

• 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_slave_sg(9)
• atc_tx_status(9)
• atc_alloc_chan_resources(9)
• atc_free_chan_resources(9)
• at_dma_off(9)

ngl this whole page lives under ./drivers/dma — that's the directory, bestie, go look 👀

and that's the page!! 🌈 slayed, ate, left no crumbs. this iconic piece of documentation is stamped October 2026 and lives at ./drivers/dma, and the page itself is atc_prep_dma_cyclic(9) — mwah, love u, go prep some cyclic DMA 💜🎀✨