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For the memcpy-toIO > helpers, could you please clarify the specific reason for adding a dmb despite > the documented no-ordering contract? Is the concern that some drivers may > be relying on ordering across memcpy_toio_*() today even though the API > does not guarantee it, and that we should cover those cases defensively? I think given how arm implements them today the iocopy's are actually the _relaxed variations.. I wonder if this matters to any user? Jason