diff options
Diffstat (limited to 'Documentation/DocBook/v4l/vidioc-querybuf.xml')
| -rw-r--r-- | Documentation/DocBook/v4l/vidioc-querybuf.xml | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/Documentation/DocBook/v4l/vidioc-querybuf.xml b/Documentation/DocBook/v4l/vidioc-querybuf.xml index e649805a4908..5c104d42d31c 100644 --- a/Documentation/DocBook/v4l/vidioc-querybuf.xml +++ b/Documentation/DocBook/v4l/vidioc-querybuf.xml @@ -61,6 +61,10 @@ buffer at any time after buffers have been allocated with the to the number of buffers allocated with &VIDIOC-REQBUFS; (&v4l2-requestbuffers; <structfield>count</structfield>) minus one. The <structfield>reserved</structfield> field should to set to 0. +When using the <link linkend="planar-apis">multi-planar API</link>, the +<structfield>m.planes</structfield> field must contain a userspace pointer to an +array of &v4l2-plane; and the <structfield>length</structfield> field has +to be set to the number of elements in that array. After calling <constant>VIDIOC_QUERYBUF</constant> with a pointer to this structure drivers return an error code or fill the rest of the structure.</para> @@ -70,11 +74,13 @@ the structure.</para> <constant>V4L2_BUF_FLAG_QUEUED</constant> and <constant>V4L2_BUF_FLAG_DONE</constant> flags will be valid. The <structfield>memory</structfield> field will be set to the current -I/O method, the <structfield>m.offset</structfield> +I/O method. For the single-planar API, the <structfield>m.offset</structfield> contains the offset of the buffer from the start of the device memory, -the <structfield>length</structfield> field its size. The driver may -or may not set the remaining fields and flags, they are meaningless in -this context.</para> +the <structfield>length</structfield> field its size. For the multi-planar API, +fields <structfield>m.mem_offset</structfield> and +<structfield>length</structfield> in the <structfield>m.planes</structfield> +array elements will be used instead. The driver may or may not set the remaining +fields and flags, they are meaningless in this context.</para> <para>The <structname>v4l2_buffer</structname> structure is specified in <xref linkend="buffer" />.</para> |