media: videobuf2-core.h: improve buf_struct_size documentation

Explicitly document that the driver-specific buffer structure
must start with the subsystem-specific struct (vb2_v4l2_buffer
in the case of V4L2).

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Hans Verkuil 2020-02-20 10:34:26 +01:00 committed by Mauro Carvalho Chehab
parent 6af5bcd379
commit 1583c793af

View File

@ -509,8 +509,11 @@ struct vb2_buf_ops {
* by the vb2 core.
* @buf_struct_size: size of the driver-specific buffer structure;
* "0" indicates the driver doesn't want to use a custom buffer
* structure type. for example, ``sizeof(struct vb2_v4l2_buffer)``
* will be used for v4l2.
* structure type. In that case a subsystem-specific struct
* will be used (in the case of V4L2 that is
* ``sizeof(struct vb2_v4l2_buffer)``). The first field of the
* driver-specific buffer structure must be the subsystem-specific
* struct (vb2_v4l2_buffer in the case of V4L2).
* @timestamp_flags: Timestamp flags; ``V4L2_BUF_FLAG_TIMESTAMP_*`` and
* ``V4L2_BUF_FLAG_TSTAMP_SRC_*``
* @gfp_flags: additional gfp flags used when allocating the buffers.