fix(dmac): Use inline asm for compiler fences in DMAC#985
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jbeaurivage wants to merge 3 commits intoatsamd-rs:masterfrom
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fix(dmac): Use inline asm for compiler fences in DMAC#985jbeaurivage wants to merge 3 commits intoatsamd-rs:masterfrom
jbeaurivage wants to merge 3 commits intoatsamd-rs:masterfrom
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Looks good @jbeaurivage , but maybe, its best to put the fence functions near the crate root for future use by other peripherals should we need to in future? - Or is this specific to DMAC? |
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I think this should remain a DMAC-specific thing, as peripherals are expected to control DMA through the DMAC API. |
Signed-off-by: Justin Beaurivage <code@beaurivage.io>
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Summary
According to this discussion, it seems
core::sync::atomic::{fence, compiler_fence}aren't a strong guarantee that the compiler won't reorder memory accesses beyond the fence. The suggested fix is to add an inline assembly call, which apparently guarantees there won't be any memory accesses beyond the asm call.