dma_need_unmap(9)

💅 dma_need_unmap — like, does this device even need dma_unmap_*?? 👀

okay bestie, welcome to the Kernel API Manual ✨ — this one's short and sweet, but it's important, so pay attention 🫶

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✨ NAME ✨

dma_need_unmap — does this device need dma_unmap_* operations 💭

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🦋 SYNOPSIS 🦋

bool dma_need_unmap (struct device *dev );

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🎀 ARGUMENTS 🎀

• dev — the device to check 🔍 like, the one you're wondering about

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💖 DESCRIPTION 💖

so here's the tea ☕ — if this function returns false, drivers can skip calling dma_unmap_* after finishing an I/O. literally just don't bother, it's giving "no notes" 💅

⚠️ but listen — this function must be called after all mappings that might need to be unmapped have been performed. like, all of them. order matters, bestie, don't come for me 😭

ngl that's the whole vibe: check first, then decide whether the unmap era is even happening 🌸

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👑 SEE ALSO 👑

• ./kernel/dma/mapping.c — the source file, the main character 🧚
• dmam_free_coherent(9)
• dmam_alloc_attrs(9)
• dma_map_sg_attrs(9)
• dma_map_sgtable(9)
• dma_can_mmap(9)
• dma_mmap_attrs(9)
• dma_addressing_limited(9)

all of these? obsessed. go read them, iykyk 🔥

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and that's the whole page, bestie 🎀 this little gem lives in ./kernel/dma and the version/date stamp on it is October 2026 — so yeah, it's basically brand new, slay 💜✨