media: vb2: add (un)prepare_streaming queue ops

When userspace called VIDIOC_STREAMON, then you want to claim any streaming
resources needed and validate the video pipeline. Waiting for
start_streaming to be called is too late, since that can be postponed
until the required minimum of buffers is queued.

So add a prepare_streaming op (optional) that can be used for that
purpose, and a matching unprepare_streaming op (optional) that can
release any claimed resources. The unprepare_streaming op is called
when VIDIOC_STREAMOFF is called and q->streaming is 1, or when the
filehandle is closed while q->streaming is 1.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 3253bd2f6fee..4b6a9d2ea372 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -386,6 +386,12 @@ struct vb2_buffer {
  *			the buffer contents will be ignored anyway.
  * @buf_cleanup:	called once before the buffer is freed; drivers may
  *			perform any additional cleanup; optional.
+ * @prepare_streaming:	called once to prepare for 'streaming' state; this is
+ *			where validation can be done to verify everything is
+ *			okay and streaming resources can be claimed. It is
+ *			called when the VIDIOC_STREAMON ioctl is called. The
+ *			actual streaming starts when @start_streaming is called.
+ *			Optional.
  * @start_streaming:	called once to enter 'streaming' state; the driver may
  *			receive buffers with @buf_queue callback
  *			before @start_streaming is called; the driver gets the
@@ -405,6 +411,10 @@ struct vb2_buffer {
  *			callback by calling vb2_buffer_done() with either
  *			%VB2_BUF_STATE_DONE or %VB2_BUF_STATE_ERROR; may use
  *			vb2_wait_for_all_buffers() function
+ * @unprepare_streaming:called as counterpart to @prepare_streaming; any claimed
+ *			streaming resources can be released here. It is
+ *			called when the VIDIOC_STREAMOFF ioctls is called or
+ *			when the streaming filehandle is closed. Optional.
  * @buf_queue:		passes buffer vb to the driver; driver may start
  *			hardware operation on this buffer; driver should give
  *			the buffer back by calling vb2_buffer_done() function;
@@ -432,8 +442,10 @@ struct vb2_ops {
 	void (*buf_finish)(struct vb2_buffer *vb);
 	void (*buf_cleanup)(struct vb2_buffer *vb);
 
+	int (*prepare_streaming)(struct vb2_queue *q);
 	int (*start_streaming)(struct vb2_queue *q, unsigned int count);
 	void (*stop_streaming)(struct vb2_queue *q);
+	void (*unprepare_streaming)(struct vb2_queue *q);
 
 	void (*buf_queue)(struct vb2_buffer *vb);
 
@@ -641,8 +653,10 @@ struct vb2_queue {
 	u32				cnt_queue_setup;
 	u32				cnt_wait_prepare;
 	u32				cnt_wait_finish;
+	u32				cnt_prepare_streaming;
 	u32				cnt_start_streaming;
 	u32				cnt_stop_streaming;
+	u32				cnt_unprepare_streaming;
 #endif
 };