STRUCT EP93XX_DMA_CHAN(9)

📦 version 7.3.1, in nixpkgs unstable

💖 struct ep93xx_dma_chan(9) 💖

okay so bestie, welcome to the Kernel API Manual ✨ today we're learning about struct ep93xx_dma_chan — literally an EP93xx DMA M2P/M2M channel, and she is that girl 🎀

✨ NAME ✨

struct ep93xx_dma_chan — an EP93xx DMA M2P/M2M channel 👑

🦋 SYNOPSIS 🦋

struct ep93xx_dma_chan {
    struct dma_chan                 chan;
    const struct ep93xx_dma_engine  *edma;
    void __iomem                    *regs;
    struct ep93xx_dma_chan_cfg      dma_cfg;
    int irq;
    struct clk                      *clk;
    struct tasklet_struct           tasklet;
    spinlock_t lock;
    unsigned long                   flags;
  #define EP93XX_DMA_IS_CYCLIC            0;
    int buffer;
    struct list_head                active;
    struct list_head                queue;
    struct list_head                free_list;
    u32 runtime_addr;
    u32 runtime_ctrl;
    struct dma_slave_config         slave_config;
 };

she's got range, she's got fields, she's iconic 💅

🌸 Members 🌸

  • chan — the dmaengine API channel, the main character of the whole struct fr fr 👑
  • edma — pointer to the engine device, iykyk 🧚
  • regs — memory mapped registers, lowkey where the magic happens ✨
  • dma_cfg — channel number, direction — the whole vibe check of this channel 🎀
  • irq — interrupt number of the channel 🦋
  • clk — clock used by this channel, she needs her energy ⭐
  • tasklet — channel specific tasklet used for callbacks 💖
  • lock — lock protecting the fields following 🔒 (respect her boundaries bestie)
  • flags — flags for the channel 🌈
  • buffer — which buffer to use next (0/1), a little binary moment 💀
  • active — flattened chain of descriptors currently being processed 🔥
  • queue — pending descriptors which are handled next, the waiting room 🫶
  • free_list — list of free descriptors which can be used, the available pool 🍓
  • runtime_addr — physical address currently used as dest/src (M2M only). This is set via .device_config before slave operation is prepared 🙈
  • runtime_ctrl — M2M runtime values for the control register 💜
  • slave_config — slave configuration 💅

⭐ Description ⭐

so here's the tea ☕ the EP93xx DMA controller doesn't support real chained DMA descriptors, so we will have a slightly different scheme here: active points to a head of flattened DMA descriptor chain 💫

queue holds pending transactions. These are linked through the first descriptor in the chain. When a descriptor is moved to the active queue, the first and chained descriptors are flattened into a single list 🔥 — no cap, that's literally how she works ✨

💜 SEE ALSO 💜

go read those fr fr, they're all linked in the same ./drivers/dma cinematic universe 🎬

okay bestie that's the whole page, hope u slayed the vibe check 💖 this came straight out of ./drivers/dma, dated October 2026, and it's part of the Kernel API Manual — mwah, study up, ily, bye 👑✨🎀

📦 where this page comes from