diff options
Diffstat (limited to 'Documentation/DocBook/v4l/vidioc-qbuf.xml')
| -rw-r--r-- | Documentation/DocBook/v4l/vidioc-qbuf.xml | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/Documentation/DocBook/v4l/vidioc-qbuf.xml b/Documentation/DocBook/v4l/vidioc-qbuf.xml index ab691ebf3b9..f2b11f8a403 100644 --- a/Documentation/DocBook/v4l/vidioc-qbuf.xml +++ b/Documentation/DocBook/v4l/vidioc-qbuf.xml @@ -64,7 +64,8 @@ zero to the number of buffers allocated with &VIDIOC-REQBUFS; contents of the struct <structname>v4l2_buffer</structname> returned by a &VIDIOC-QUERYBUF; ioctl will do as well. When the buffer is intended for output (<structfield>type</structfield> is -<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant> or +<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant>, +<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE</constant>, or <constant>V4L2_BUF_TYPE_VBI_OUTPUT</constant>) applications must also initialize the <structfield>bytesused</structfield>, <structfield>field</structfield> and @@ -75,7 +76,11 @@ supports capturing from specific video inputs and you want to specify a video input, then <structfield>flags</structfield> should be set to <constant>V4L2_BUF_FLAG_INPUT</constant> and the field <structfield>input</structfield> must be initialized to the desired input. -The <structfield>reserved</structfield> field must be set to 0. +The <structfield>reserved</structfield> field must be 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 a filled-in array of &v4l2-plane; and the <structfield>length</structfield> +field must be set to the number of elements in that array. </para> <para>To enqueue a <link linkend="mmap">memory mapped</link> @@ -93,10 +98,13 @@ structure the driver sets the buffer applications set the <structfield>memory</structfield> field to <constant>V4L2_MEMORY_USERPTR</constant>, the <structfield>m.userptr</structfield> field to the address of the -buffer and <structfield>length</structfield> to its size. -When <constant>VIDIOC_QBUF</constant> is called with a pointer to this -structure the driver sets the <constant>V4L2_BUF_FLAG_QUEUED</constant> -flag and clears the <constant>V4L2_BUF_FLAG_MAPPED</constant> and +buffer and <structfield>length</structfield> to its size. When the multi-planar +API is used, <structfield>m.userptr</structfield> and +<structfield>length</structfield> members of the passed array of &v4l2-plane; +have to be used instead. When <constant>VIDIOC_QBUF</constant> is called with +a pointer to this structure the driver sets the +<constant>V4L2_BUF_FLAG_QUEUED</constant> flag and clears the +<constant>V4L2_BUF_FLAG_MAPPED</constant> and <constant>V4L2_BUF_FLAG_DONE</constant> flags in the <structfield>flags</structfield> field, or it returns an error code. This ioctl locks the memory pages of the buffer in physical memory, @@ -115,7 +123,9 @@ remaining fields or returns an error code. The driver may also set <constant>V4L2_BUF_FLAG_ERROR</constant> in the <structfield>flags</structfield> field. It indicates a non-critical (recoverable) streaming error. In such case the application may continue as normal, but should be aware that data in the -dequeued buffer might be corrupted.</para> +dequeued buffer might be corrupted. When using the multi-planar API, the +planes array does not have to be passed; the <structfield>m.planes</structfield> +member must be set to NULL in that case.</para> <para>By default <constant>VIDIOC_DQBUF</constant> blocks when no buffer is in the outgoing queue. When the |