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| author | Daniel Stone <daniels@collabora.com> | 2023-08-03 16:47:28 +0100 |
|---|---|---|
| committer | Simon Ser <contact@emersion.fr> | 2023-08-21 17:10:33 +0200 |
| commit | 09902f3a1f83085006742f18388b5098c1b57132 (patch) | |
| tree | 8ec84afea9dd6cedadf44fe4452d4f21e02b9d47 /Documentation/driver-api | |
| parent | d7a407bc9ba30628eb699170e21d50c701c0e872 (diff) | |
| download | linux-09902f3a1f83085006742f18388b5098c1b57132.tar.gz | |
doc: dma-buf: Rewrite intro section a little
Make it a little bit more clear what's going on and fix some formatting.
Signed-off-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Simon Ser <contact@emersion.fr>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20230803154908.105124-3-daniels@collabora.com
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/dma-buf.rst | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst index f92a32d095d965..862dbc2759d0e7 100644 --- a/Documentation/driver-api/dma-buf.rst +++ b/Documentation/driver-api/dma-buf.rst @@ -5,14 +5,22 @@ The dma-buf subsystem provides the framework for sharing buffers for hardware (DMA) access across multiple device drivers and subsystems, and for synchronizing asynchronous hardware access. -This is used, for example, by drm "prime" multi-GPU support, but is of -course not limited to GPU use cases. - -The three main components of this are: (1) dma-buf, representing a -sg_table and exposed to userspace as a file descriptor to allow passing -between devices, (2) fence, which provides a mechanism to signal when -one device has finished access, and (3) reservation, which manages the -shared or exclusive fence(s) associated with the buffer. +As an example, it is used extensively by the DRM subsystem to exchange +buffers between processes, contexts, library APIs within the same +process, and also to exchange buffers with other subsystems such as +V4L2. + +This document describes the way in which kernel subsystems can use and +interact with the three main primitives offered by dma-buf: + + - dma-buf, representing a sg_table and exposed to userspace as a file + descriptor to allow passing between processes, subsystems, devices, + etc; + - dma-fence, providing a mechanism to signal when an asynchronous + hardware operation has completed; and + - dma-resv, which manages a set of dma-fences for a particular dma-buf + allowing implicit (kernel-ordered) synchronization of work to + preserve the illusion of coherent access Shared DMA Buffers ------------------ |