[media] Add multi-planar API documentation
Add DocBook documentation for the new multi-planar API extensions to the Video for Linux 2 API DocBook. Signed-off-by: Pawel Osciak <pawel@osciak.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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Mauro Carvalho Chehab
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c4c0a78d45
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@@ -61,6 +61,10 @@ buffer at any time after buffers have been allocated with the
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to the number of buffers allocated with &VIDIOC-REQBUFS;
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(&v4l2-requestbuffers; <structfield>count</structfield>) minus one.
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The <structfield>reserved</structfield> field should to set to 0.
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When using the <link linkend="planar-apis">multi-planar API</link>, the
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<structfield>m.planes</structfield> field must contain a userspace pointer to an
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array of &v4l2-plane; and the <structfield>length</structfield> field has
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to be set to the number of elements in that array.
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After calling <constant>VIDIOC_QUERYBUF</constant> with a pointer to
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this structure drivers return an error code or fill the rest of
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the structure.</para>
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@@ -70,11 +74,13 @@ the structure.</para>
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<constant>V4L2_BUF_FLAG_QUEUED</constant> and
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<constant>V4L2_BUF_FLAG_DONE</constant> flags will be valid. The
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<structfield>memory</structfield> field will be set to the current
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I/O method, the <structfield>m.offset</structfield>
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I/O method. For the single-planar API, the <structfield>m.offset</structfield>
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contains the offset of the buffer from the start of the device memory,
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the <structfield>length</structfield> field its size. The driver may
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or may not set the remaining fields and flags, they are meaningless in
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this context.</para>
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the <structfield>length</structfield> field its size. For the multi-planar API,
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fields <structfield>m.mem_offset</structfield> and
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<structfield>length</structfield> in the <structfield>m.planes</structfield>
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array elements will be used instead. The driver may or may not set the remaining
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fields and flags, they are meaningless in this context.</para>
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<para>The <structname>v4l2_buffer</structname> structure is
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specified in <xref linkend="buffer" />.</para>
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