[PATCH] videobuf2-core: add queue_busy/idle queue ops

[Hans Verkuil <hverkuil@xxxxxxxxx>]

Some controls (ROTATE) change the buffer layout. This means that they cannot
be set when buffers are allocated. This can be achieved by calling
v4l2_ctrl_grab(ctrl, true) when the queue becomes busy (i.e. the first buffer
is allocated) and v4l2_ctrl_grab(ctrl, false) when the queue becomes idle (i.e.
the last buffer is released).

However, we do not have such queue ops at the moment. This patch adds a queue_busy
and a queue_idle op.

Note that currently queue_busy returns a void, so it assumes that it can't return
an error.

Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
Jacob, this has only been compile-tested. It's best if you add this patch to your
rockchip-rga patch series and test it there.
---
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 14f83cecfa92..e8ad0e9f78d2 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -665,6 +665,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 	}

 	if (*count == 0 || q->num_buffers != 0 || q->memory != memory) {
+		num_buffers = q->num_buffers;
 		/*
 		 * We already have buffers allocated, so first check if they
 		 * are not in use and can be freed.
@@ -686,6 +687,8 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 		mutex_unlock(&q->mmap_lock);
 		if (ret)
 			return ret;
+		if (num_buffers)
+			call_void_qop(q, queue_idle, q);

 		/*
 		 * In case of REQBUFS(0) return immediately without calling
@@ -752,6 +755,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 		 */
 	}

+	call_void_qop(q, queue_busy, q);
 	mutex_lock(&q->mmap_lock);
 	q->num_buffers = allocated_buffers;

@@ -762,6 +766,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 		 */
 		__vb2_queue_free(q, allocated_buffers);
 		mutex_unlock(&q->mmap_lock);
+		call_void_qop(q, queue_idle, q);
 		return ret;
 	}
 	mutex_unlock(&q->mmap_lock);
@@ -842,6 +847,8 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 		 */
 	}

+	if (!q->num_buffers)
+		call_void_qop(q, queue_busy, q);
 	mutex_lock(&q->mmap_lock);
 	q->num_buffers += allocated_buffers;

@@ -852,6 +859,8 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 		 */
 		__vb2_queue_free(q, allocated_buffers);
 		mutex_unlock(&q->mmap_lock);
+		if (!q->num_buffers)
+			call_void_qop(q, queue_idle, q);
 		return -ENOMEM;
 	}
 	mutex_unlock(&q->mmap_lock);
@@ -2011,11 +2020,15 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read);
 static int __vb2_cleanup_fileio(struct vb2_queue *q);
 void vb2_core_queue_release(struct vb2_queue *q)
 {
+	bool was_busy = vb2_is_busy(q);
+
 	__vb2_cleanup_fileio(q);
 	__vb2_queue_cancel(q);
 	mutex_lock(&q->mmap_lock);
 	__vb2_queue_free(q, q->num_buffers);
 	mutex_unlock(&q->mmap_lock);
+	if (was_busy)
+		call_void_qop(q, queue_idle, q);
 }
 EXPORT_SYMBOL_GPL(vb2_core_queue_release);

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index cb97c224be73..3aa039fd29ce 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -315,6 +315,10 @@ struct vb2_buffer {
  *			\*num_buffers are being allocated additionally to
  *			q->num_buffers. If either \*num_planes or the requested
  *			sizes are invalid callback must return %-EINVAL.
+ * @queue_busy:		called when the queue becomes busy (i.e. at least one
+ *			buffer has been allocated).
+ * @queue_idle:		called when the last buffer from the queue is released
+ *			and the queue is no longer marked busy.
  * @wait_prepare:	release any locks taken while calling vb2 functions;
  *			it is called before an ioctl needs to wait for a new
  *			buffer to arrive; required to avoid a deadlock in
@@ -380,6 +384,8 @@ struct vb2_ops {
 	int (*queue_setup)(struct vb2_queue *q,
 			   unsigned int *num_buffers, unsigned int *num_planes,
 			   unsigned int sizes[], struct device *alloc_devs[]);
+	void (*queue_busy)(struct vb2_queue *q);
+	void (*queue_idle)(struct vb2_queue *q);

 	void (*wait_prepare)(struct vb2_queue *q);
 	void (*wait_finish)(struct vb2_queue *q);
@@ -547,6 +553,8 @@ struct vb2_queue {
 	 * called. Used to check for unbalanced ops.
 	 */
 	u32				cnt_queue_setup;
+	u32				cnt_queue_busy;
+	u32				cnt_queue_idle;
 	u32				cnt_wait_prepare;
 	u32				cnt_wait_finish;
 	u32				cnt_start_streaming;