STRUCT XDMA_DESC(9)

✨ struct xdma_desc(9) ✨

okay so bestie, this is a page straight out of the Kernel API Manual and it's literally all about struct xdma_desc — the DMA desc structure. yes, THE descriptor struct. buckle up 💅

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🌸 NAME 🌸

struct xdma_desc — DMA desc structure

like, it's the descriptor. for DMA. that's the whole vibe. 🦋

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🎀 SYNOPSIS 🎀

here's the literal shape of it, no cap, copy-pasted from the source of truth:

struct xdma_desc {
    struct virt_dma_desc            vdesc;
    struct xdma_chan                *chan;
    enum dma_transfer_direction     dir;
    struct xdma_desc_block          *desc_blocks;
    u32 dblk_num;
    u32 desc_num;
    u32 completed_desc_num;
    bool cyclic;
    bool interleaved_dma;
    u32 periods;
    u32 period_size;
    u32 frames_left;
    bool error;
 };

look at her. thirteen fields. main character energy fr fr 👑

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💖 Members 💖

time for the member-by-member breakdown, bestie — every single one, let's go 🫶

• vdesc — the Virtual DMA descriptor. iconic. literally the virtual layer's descriptor 💫
• chan — DMA channel pointer. it points at the channel, iykyk 🔥
• dir — Transferring direction of the request. where the data's headed, basically 🧭
• desc_blocks — Hardware descriptor blocks. the actual hardware-side blocks 🌈
• dblk_num — Number of hardware descriptor blocks. count 'em 🍓
• desc_num — Number of hardware descriptors. more counting, we love to see it ⭐
• completed_desc_num — Completed hardware descriptors. the ones that are done done ✅
• cyclic — Cyclic transfer vs. scatter-gather. which flavor of transfer we're on 🔄
• interleaved_dma — Interleaved DMA transfer. the interleaved situation 🌀
• periods — Number of periods in the cyclic transfer. how many periods, in the cyclic transfer 💜
• period_size — Size of a period in bytes in cyclic transfers. bytes! per period! in cyclic transfers! 📏
• frames_left — Number of frames left in interleaved DMA transfer. frames remaining, interleaved DMA transfer, you get it 🎬
• error — tx error flag. it's the error flag. for tx. 😭

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🔍 SEE ALSO 🔍

okay so if you're going deeper (and you ARE, I can tell), the Kernel file to look at is ./drivers/dma/xilinx/xdma.c — that's where the lore lives. and here's the whole friend group, every single one, not skipping a single bestie 🫶:

• struct xdma_desc_block(9)
• struct xdma_chan(9)
• struct xdma_device(9)
• xdma_link_sg_desc_blocks(9)
• xdma_link_cyclic_desc_blocks(9)
• xdma_channel_init(9)
• xdma_free_desc(9)
• xdma_alloc_desc(9)
• xdma_xfer_start(9)
• xdma_xfer_stop(9)
• xdma_alloc_channels(9)
• xdma_issue_pending(9)
• xdma_terminate_all(9)
• xdma_synchronize(9)
• xdma_fill_descs(9)
• xdma_prep_device_sg(9)
• xdma_prep_dma_cyclic(9)
• xdma_prep_interleaved_dma(9)
• xdma_device_config(9)
• xdma_free_chan_resources(9)
• xdma_alloc_chan_resources(9)
• xdma_channel_isr(9)
• xdma_irq_fini(9)
• xdma_set_vector_reg(9)
• xdma_irq_init(9)
• xdma_disable_user_irq(9)
• xdma_enable_user_irq(9)
• xdma_get_user_irq(9)
• xdma_remove(9)
• xdma_probe(9)

no because that's a LOT of cross-references and honestly? slay. read them all. periodt 💅

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ok that's the whole page bestie, nothing skipped, nothing hidden 💖

and that's the wrap, bestie — this one came from ./drivers/dma/xilinx, dated October 2026, and it's struct xdma_desc(9) all the way down. mwah 💋✨