From e3b1b4e732e18befcfa428bac1c487f681fbc36a Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Wed, 19 Sep 2012 11:14:39 -0300 Subject: [PATCH] [media] DocBook: various updates w.r.t. v4l2_buffer and multiplanar Clarify the behavior of v4l2_buffer in the multiplanar case, including fixing a false statement: you can't set m.planes to NULL when calling DQBUF. Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- Documentation/DocBook/media/v4l/io.xml | 6 ++++-- Documentation/DocBook/media/v4l/vidioc-qbuf.xml | 3 +-- Documentation/DocBook/media/v4l/vidioc-querybuf.xml | 11 +++++++---- 3 files changed, 12 insertions(+), 8 deletions(-) diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml index 97f785add841..b5d1cbdc558b 100644 --- a/Documentation/DocBook/media/v4l/io.xml +++ b/Documentation/DocBook/media/v4l/io.xml @@ -677,8 +677,10 @@ memory, set by the application. See for details. length Size of the buffer (not the payload) in bytes for the - single-planar API. For the multi-planar API should contain the - number of elements in the planes array. + single-planar API. For the multi-planar API the application sets + this to the number of elements in the planes + array. The driver will fill in the actual number of valid elements in + that array. diff --git a/Documentation/DocBook/media/v4l/vidioc-qbuf.xml b/Documentation/DocBook/media/v4l/vidioc-qbuf.xml index 6a821a65a5ae..2d37abefce13 100644 --- a/Documentation/DocBook/media/v4l/vidioc-qbuf.xml +++ b/Documentation/DocBook/media/v4l/vidioc-qbuf.xml @@ -121,8 +121,7 @@ remaining fields or returns an error code. The driver may also set 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. When using the multi-planar API, the -planes array does not have to be passed; the m.planes -member must be set to NULL in that case. +planes array must be passed in as well. By default VIDIOC_DQBUF blocks when no buffer is in the outgoing queue. When the diff --git a/Documentation/DocBook/media/v4l/vidioc-querybuf.xml b/Documentation/DocBook/media/v4l/vidioc-querybuf.xml index 6e414d7b6df7..a597155c052d 100644 --- a/Documentation/DocBook/media/v4l/vidioc-querybuf.xml +++ b/Documentation/DocBook/media/v4l/vidioc-querybuf.xml @@ -48,8 +48,8 @@ Description - This ioctl is part of the memory -mapping I/O method. It can be used to query the status of a + This ioctl is part of the streaming + I/O method. It can be used to query the status of a buffer at any time after buffers have been allocated with the &VIDIOC-REQBUFS; ioctl. @@ -71,6 +71,7 @@ the structure. In the flags field the V4L2_BUF_FLAG_MAPPED, +V4L2_BUF_FLAG_PREPARED, V4L2_BUF_FLAG_QUEUED and V4L2_BUF_FLAG_DONE flags will be valid. The memory field will be set to the current @@ -79,8 +80,10 @@ contains the offset of the buffer from the start of the device memory, the length field its size. For the multi-planar API, fields m.mem_offset and length in the m.planes -array elements will be used instead. The driver may or may not set the remaining -fields and flags, they are meaningless in this context. +array elements will be used instead and the length +field of &v4l2-buffer; is set to the number of filled-in array elements. +The driver may or may not set the remaining fields and flags, they are +meaningless in this context. The v4l2_buffer structure is specified in . -- GitLab