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Viewing changes to Documentation/DocBook/v4l/vidioc-querybuf.xml

  • Committer: Bazaar Package Importer
  • Author(s): Paolo Pisati
  • Date: 2011-06-29 15:23:51 UTC
  • mfrom: (26.1.1 natty-proposed)
  • Revision ID: james.westby@ubuntu.com-20110629152351-xs96tm303d95rpbk
Tags: 3.0.0-1200.2
* Rebased against 3.0.0-6.7
* BSP from TI based on 3.0.0

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Documentation/DocBook/v4l/vidioc-querybuf.xml
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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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<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>