STRUCT AT_DESC(9)

💅 struct at_desc(9) — Kernel API Manual, bestie edition 🎀

okay so welcome to the struct at_desc(9) page!! it's giving "software descriptor" energy and honestly? it's iconic. this is the kernel API manual entry, so grab a strawberry drink 🍓 and let's get into it ✨

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✨ NAME ✨

struct at_desc — the software descriptor. that's it, that's the vibe 💖

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🌸 SYNOPSIS 🌸

struct at_desc {
    struct virt_dma_desc vd;
    struct at_dma_chan *atchan;
    size_t total_len;
    unsigned int                    sglen;
    size_t boundary;
    size_t dst_hole;
    size_t src_hole;
    bool memset_buffer;
    dma_addr_t memset_paddr;
    int *memset_vaddr;
    struct atdma_sg                 sg[];
 };

look at her. main character struct fr fr 👑

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🦋 Members 🦋

• vd — pointer to the virtual dma descriptor. lowkey the VIP pass of this struct 💅
• atchan — pointer to the atmel dma channel. yup, that's the atmel one 🧚
• total_len — total transaction byte count. the whole entire size, no cap.
• sglen — number of sg entries. count 'em 🔥
• boundary — number of transfers to perform before the automatic address increment operation. yes bestie, it's a before thing 🫶
• dst_hole — value to add to the destination address when the boundary has been reached. once you hit the boundary, this gets added 💜
• src_hole — value to add to the source address when the boundary has been reached. same deal, but source side ⭐
• memset_buffer — buffer used for the memset operation. the memset one, obviously 🙈
• memset_paddr — physical address of the buffer used for the memset operation. the physical address of it 🎀
• memset_vaddr — virtual address of the buffer used for the memset operation. and here's the virtual address of that same buffer 🌈
• sg — array of sgs. literally an array of them 😭

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🔍 SEE ALSO 🔍

okay so there are SO many siblings, here's the whole family, no skips:

• Kernel file ./drivers/dma/at_hdmac.c
• struct atdma_sg(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_prep_dma_cyclic(9)
• atc_tx_status(9)
• atc_alloc_chan_resources(9)
• atc_free_chan_resources(9)
• at_dma_off(9)

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go read them all bestie, iykwim 😌

and that's the page!! mwah 💋 this one ships from ./drivers/dma, dated October 2026 — signed, sealed, struct at_desc(9) 🫶✨