diff options
| author | Hirokazu Honda <hiroh@chromium.org> | 2021-08-26 20:25:31 +0900 |
|---|---|---|
| committer | Laurent Pinchart <laurent.pinchart@ideasonboard.com> | 2021-08-30 18:08:02 +0300 |
| commit | 86a47fdcd97350bd979a4d6b00124330a3b02441 (patch) | |
| tree | 5019efc31e378911c92ffe2b052f3ab9b60faa63 /src/libcamera/framebuffer.cpp | |
| parent | a000a1f6e3208515200aaae6ca8128471c6ed9f3 (diff) | |
libcamera: framebuffer: Add offset to FrameBuffer::Plane
This adds offset to FrameBuffer::Plane. It enables representing frame
buffers that store planes in the same dmabuf at different offsets, as
for instance required by the V4L2 NV12 pixel format.
Signed-off-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Diffstat (limited to 'src/libcamera/framebuffer.cpp')
| -rw-r--r-- | src/libcamera/framebuffer.cpp | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/src/libcamera/framebuffer.cpp b/src/libcamera/framebuffer.cpp index b401c50e..bf7a52ad 100644 --- a/src/libcamera/framebuffer.cpp +++ b/src/libcamera/framebuffer.cpp @@ -131,7 +131,7 @@ FrameBuffer::Private::Private() * * The static information describes the memory planes that make a frame. The * planes are specified when creating the FrameBuffer and are expressed as a set - * of dmabuf file descriptors and length. + * of dmabuf file descriptors, offset and length. * * The dynamic information is grouped in a FrameMetadata instance. It is updated * during the processing of a queued capture request, and is valid from the @@ -151,18 +151,23 @@ FrameBuffer::Private::Private() * * Planar pixel formats use multiple memory regions to store the different * colour components of a frame. The Plane structure describes such a memory - * region by a dmabuf file descriptor and a length. A FrameBuffer then - * contains one or multiple planes, depending on the pixel format of the - * frames it is meant to store. + * region by a dmabuf file descriptor, an offset within the dmabuf and a length. + * A FrameBuffer then contains one or multiple planes, depending on the pixel + * format of the frames it is meant to store. + * + * The offset identifies the location of the plane data from the start of the + * memory referenced by the dmabuf file descriptor. Multiple planes may be + * stored in the same dmabuf, in which case they will reference the same dmabuf + * and different offsets. No two planes may overlap, as specified by their + * offset and length. * * To support DMA access, planes are associated with dmabuf objects represented * by FileDescriptor handles. The Plane class doesn't handle mapping of the * memory to the CPU, but applications and IPAs may use the dmabuf file * descriptors to map the plane memory with mmap() and access its contents. * - * \todo Once we have a Kernel API which can express offsets within a plane - * this structure shall be extended to contain this information. See commit - * 83148ce8be55e for initial documentation of this feature. + * \todo Specify how an application shall decide whether to use a single or + * multiple dmabufs, based on the camera requirements. */ /** @@ -171,6 +176,11 @@ FrameBuffer::Private::Private() */ /** + * \var FrameBuffer::Plane::offset + * \brief The plane offset in bytes +*/ + +/** * \var FrameBuffer::Plane::length * \brief The plane length in bytes */ |