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For supporting the explicit in-kernel copy of PCM buffer data, and also for further code refactoring, three new PCM ops, copy_user, copy_kernel and fill_silence, are introduced. The old copy and silence ops will be deprecated and removed later once when all callers are converted. The copy_kernel ops is the new one, and it's supposed to transfer the PCM data from the given kernel buffer to the hardware ring-buffer (or vice-versa depending on the stream direction), while the copy_user ops is equivalent with the former copy ops, to transfer the data from the user-space buffer. The major difference of the new copy_* and fill_silence ops from the previous ops is that the new ops take bytes instead of frames for size and position arguments. It has two merits: first, it allows the callback implementation often simpler (just call directly memcpy() & co), and second, it may unify the implementations of both interleaved and non-interleaved cases, as we'll see in the later patch. As of this stage, copy_kernel ops isn't referred yet, but only copy_user is used. Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Acked-by: Mark Brown <broonie@kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.