Hello I have the need to allocate a scratch buffer to mirror the content of the vb2_buffer planes (more detail on this on request). The allocation of such 'scratch' buffer should ideally be done once, at buffer creation time (and released at buffer release time ?) Looking at the videobuf2 framework implementation I noticed that the ideal entry point for this would be vb2_queue.buf_ops.init_buffer, which is called in the __vb2_queue_alloc() call path. I have noticed that the vb2_queue.buf_ops members seems to be there to be made overridable by drivers, but are instead: 1) unconditionally set by the framework in vb2_queue_init_name() 2) the core helpers are not exported hence I was wondering if this is the result some half-baked attempt to make them ovverridable or the possibility of override them was instead deprecated. As I found no traces of this in the log, I thought it was easier to send an RFC. I also checked what other entry points I could have used to allocate backing memory for a buffer, and I have considered vb2_queue.vb2_ops.buf_init which is however called in the vb2_req_prepare() call path (I'm not using the request API atm) or in the VIDIOC_PREPARE_BUF call path, which requires ad-hoc instrumentation in user space (something I would like to avoid if possibile). What do you think ? Jacopo Mondi (3): media: videobuf2: WARN if !vb2_queue.buf_ops media: Allow drivers to overwrite vb2_queue.buf_ops media: rkisp1-params: Override vb2_queue.buf_ops .../media/common/videobuf2/videobuf2-core.c | 12 ++++--- .../media/common/videobuf2/videobuf2-v4l2.c | 34 +++++++++++-------- .../platform/rockchip/rkisp1/rkisp1-params.c | 18 +++++++++- include/media/videobuf2-core.h | 7 ++++ include/media/videobuf2-v4l2.h | 8 +++++ 5 files changed, 60 insertions(+), 19 deletions(-) -- 2.45.1
