STRUCT DMA_CHAN(9)

🌈 struct dma_chan(9) 🌈💅

okay so bestie, this is literally the Kernel API Manual page for struct dma_chan(9) — and the whole vibe is “devices supply DMA channels, clients use them” ✨ no cap. It’s a kernel struct, it’s iconic, and we’re gonna walk through every single member like it’s a group-chat roll call 🫶

✨ NAME ✨

struct dma_chan — devices supply DMA channels, and clients use them 🎀 periodt.

💖 SYNOPSIS 💖

       struct dma_chan {
           struct dma_device *device;
           struct device *slave;
           dma_cookie_t cookie;
           dma_cookie_t completed_cookie;
           spinlock_t lock;
           int chan_id;
           struct dma_chan_dev *dev;
           const char *name;
         #ifdef CONFIG_DEBUG_FS;
           char *dbg_client_name;
         #endif;
           struct list_head device_node;
           struct dma_chan_percpu __percpu *local;
           int client_count;
           int table_count;
           struct dma_router *router;
           void *route_data;
           void *private;
        };

🌸 Members 🌸

• device — ptr to the DMA device that supplies this channel, and it is always !NULL — no cap, bestie 💅
• slave — ptr to the device using this channel 🫶
• cookie — last cookie value returned to the client 🍪
• completed_cookie — last completed cookie for this channel ✅
• lock — protects between config and prepare-transfer when the driver has not implemented the device_prep_config_sg callback 🔒
• chan_id — channel ID for sysfs 🆔
• dev — class device for sysfs 📁
• name — backlink name for sysfs 🏷️
• dbg_client_name — slave name for debugfs, in the format dev_name(requester's dev):channel name, for example: "2b00000.mcasp:tx" — this one lives under #ifdef CONFIG_DEBUG_FS; in the struct 🐛
• device_node — used to add this to the device chan list 🔗
• local — per-cpu pointer to a struct dma_chan_percpu ⚡
• client_count — how many clients are using this channel 👥
• table_count — number of appearances in the mem-to-mem allocation table 📊
• router — pointer to the DMA router structure 🛰️
• route_data — channel specific data for the router 🧭
• private — private data for certain client-channel associations 🙈

🦋 SEE ALSO 🦋

• Kernel file ./include/linux/dmaengine.h 📁
• dma_cookie_t(9)
• enum dma_status(9)
• enum dma_transaction_type(9)
• enum dma_transfer_direction(9)
• struct data_chunk(9)
• struct dma_interleaved_template(9)
• struct dma_vec(9)
• enum dma_ctrl_flags(9)
• enum sum_check_bits(9)
• enum sum_check_flags(9)
• enum dma_desc_metadata_mode(9)
• struct dma_chan_percpu(9)
• struct dma_router(9)
• struct dma_chan_dev(9)
• enum dma_slave_buswidth(9)
• struct dma_slave_config(9)
• enum dma_residue_granularity(9)
• struct dma_slave_caps(9)
• dma_filter_fn(9)
• struct dma_async_tx_descriptor(9)
• struct dma_tx_state(9)
• enum dmaengine_alignment(9)
• struct dma_slave_map(9)
• struct dma_filter(9)
• struct dma_device(9)
• dmaengine_prep_peripheral_dma_vec(9)
• dmaengine_prep_config_sg_safe(9)
• dmaengine_prep_config_single_safe(9)
• dmaengine_prep_dma_memset(9)
• dmaengine_terminate_all(9)
• dmaengine_terminate_async(9)
• dmaengine_synchronize(9)
• dmaengine_terminate_sync(9)
• dma_async_issue_pending(9)
• dma_async_is_tx_complete(9)
• dma_async_is_complete(9)

that’s the whole page, bestie — source/version: ./include/linux, date: October 2026, signed: struct dma_chan(9) 💖 slay and bye ✨