[PATCH v8 04/13] [media] vb2: add is_unordered callback for drivers

[Gustavo Padovan <gustavo@xxxxxxxxxxx>]

From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>

Explicit synchronization benefits a lot from ordered queues, they fit
better in a pipeline with DRM for example so create a opt-in way for
drivers notify videobuf2 that the queue is unordered.

Drivers don't need implement it if the queue is ordered.

v2: 	- improve comments for is_unordered flag (Hans)

v3: 	- make it bool (Hans)
	- create vb2_ops_set_unordered() helper

Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
---
 drivers/media/common/videobuf2/videobuf2-v4l2.c |  6 ++++++
 include/media/videobuf2-core.h                  |  6 ++++++
 include/media/videobuf2-v4l2.h                  | 10 ++++++++++
 3 files changed, 22 insertions(+)

diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 886a2d8d5c6c..68291ba8632d 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -961,6 +961,12 @@ void vb2_ops_wait_finish(struct vb2_queue *vq)
 }
 EXPORT_SYMBOL_GPL(vb2_ops_wait_finish);
 
+bool vb2_ops_set_unordered(struct vb2_queue *q)
+{
+	return true;
+}
+EXPORT_SYMBOL_GPL(vb2_ops_set_unordered);
+
 MODULE_DESCRIPTION("Driver helper framework for Video for Linux 2");
 MODULE_AUTHOR("Pawel Osciak <pawel@xxxxxxxxxx>, Marek Szyprowski");
 MODULE_LICENSE("GPL");
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 5b6c541e4e1b..46a9e674f7e1 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -370,6 +370,10 @@ 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
+ * @is_unordered:	tell if the queue is unordered, i.e. buffers can be
+ *			dequeued in a different order from how they were queued.
+ *			The default is assumed to be ordered and this function
+ *			only needs to be implemented for unordered queues.
  * @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;
@@ -393,6 +397,7 @@ struct vb2_ops {
 
 	int (*start_streaming)(struct vb2_queue *q, unsigned int count);
 	void (*stop_streaming)(struct vb2_queue *q);
+	bool (*is_unordered)(struct vb2_queue *q);
 
 	void (*buf_queue)(struct vb2_buffer *vb);
 };
@@ -566,6 +571,7 @@ struct vb2_queue {
 	u32				cnt_wait_finish;
 	u32				cnt_start_streaming;
 	u32				cnt_stop_streaming;
+	u32				cnt_is_unordered;
 #endif
 };
 
diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h
index 3d5e2d739f05..9de3c887c875 100644
--- a/include/media/videobuf2-v4l2.h
+++ b/include/media/videobuf2-v4l2.h
@@ -291,4 +291,14 @@ void vb2_ops_wait_prepare(struct vb2_queue *vq);
  */
 void vb2_ops_wait_finish(struct vb2_queue *vq);
 
+/**
+ * vb2_ops_set_unordered - helper function to mark queue as unordered
+ *
+ * @vq: pointer to &struct vb2_queue
+ *
+ * This helper just return true to notify that the driver can't deal with
+ * ordered queues.
+ */
+bool vb2_ops_set_unordered(struct vb2_queue *q);
+
 #endif /* _MEDIA_VIDEOBUF2_V4L2_H */
-- 
2.14.3