dma_request_chan_by_mask(9)

💅 dma_request_chan_by_mask(9) — from the Kernel API Manual 🎀

okay bestie, welcome to the group chat. this one's from the Kernel API Manual, and it's actually kinda short but it SLAPS. it's literally "gimme a DMA channel that matches my vibe" — no cap.

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✨ NAME ✨

dma_request_chan_by_mask — allocate a channel satisfying certain capabilities 🦋

like, you hand it a mask of capabilities and it goes off and finds you a DMA channel that actually fits the bill. main character energy fr.

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🌸 SYNOPSIS 🌸

struct dma_chan * dma_request_chan_by_mask (const dma_cap_mask_t *mask
);

that's it. that's the whole signature. one argument, one pointer back, iconic.

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🎀 ARGUMENTS 🎀

• mask — capabilities that the channel must satisfy 💖

so basically the mask is you telling the kernel "okay this is the bare minimum bestie, don't come back with anything less." the channel has to satisfy it. periodt.

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⭐ DESCRIPTION ⭐

Returns a pointer to the appropriate DMA channel on success — or an error pointer 😭

that's the whole thing. success = you got a channel pointer. not-success = you got an error pointer back, so like, do a little vibe check on it (iykyk) before you go dereferencing anything, okay? 🫶

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🌈 SEE ALSO 🌈

Kernel file ./drivers/dma/dmaengine.c — that's the home base for all of this 🏠

and then the whole extended friend group:

• dev_to_dma_chan(9)
• struct dma_chan_tbl_ent(9)
• dma_chan_is_local(9)
• min_chan(9)
• dma_channel_rebalance(9)
• balance_ref_count(9)
• dma_chan_get(9)
• dma_chan_put(9)
• dma_find_channel(9)
• dma_issue_pending_all(9)
• dma_get_slave_channel(9)
• __dma_request_channel(9)
• dma_request_chan(9)
• devm_dma_request_chan(9)
• dmaengine_get(9)
• dmaengine_put(9)
• dma_async_device_register(9)
• dma_async_device_unregister(9)
• dmaenginem_async_device_register(9)
• dma_wait_for_async_tx(9)
• dma_run_dependencies(9)

go read them all. or don't. but like, they're there 💀

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and that's the whole page bestie — no filler, all facts 🧚

this lil dma engine situation lives over in ./drivers/dma, and the docs are dated October 2026. slay, honestly. 💅✨🍓