media: add helpers for memory-to-memory media controller

A memory-to-memory pipeline device consists in three
entities: two DMA engine and one video processing entities.
The DMA engine entities are linked to a V4L interface.

This commit add a new v4l2_m2m_{un}register_media_controller
API to register this topology.

For instance, a typical mem2mem device topology would
look like this:

Device topology
- entity 1: source (1 pad, 1 link)
            type Node subtype V4L flags 0
	pad0: Source
		-> "proc":1 [ENABLED,IMMUTABLE]

- entity 3: proc (2 pads, 2 links)
            type Node subtype Unknown flags 0
	pad0: Source
		-> "sink":0 [ENABLED,IMMUTABLE]
	pad1: Sink
		<- "source":0 [ENABLED,IMMUTABLE]

- entity 6: sink (1 pad, 1 link)
            type Node subtype V4L flags 0
	pad0: Sink
		<- "proc":0 [ENABLED,IMMUTABLE]

[hans.verkuil@cisco.com: mark interface links as IMMUTABLE]

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

1 files changed, 8 insertions, 5 deletions

diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index 5f43f63fa700..69e775930fc4 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -202,7 +202,7 @@ static void v4l2_device_release(struct device *cd)
 	mutex_unlock(&videodev_lock);
 
 #if defined(CONFIG_MEDIA_CONTROLLER)
-	if (v4l2_dev->mdev) {
+	if (v4l2_dev->mdev && vdev->vfl_dir != VFL_DIR_M2M) {
 		/* Remove interfaces and interface links */
 		media_devnode_remove(vdev->intf_devnode);
 		if (vdev->entity.function != MEDIA_ENT_F_UNKNOWN)
@@ -733,19 +733,22 @@ static void determine_valid_ioctls(struct video_device *vdev)
 			BASE_VIDIOC_PRIVATE);
 }
 
-static int video_register_media_controller(struct video_device *vdev, int type)
+static int video_register_media_controller(struct video_device *vdev)
 {
 #if defined(CONFIG_MEDIA_CONTROLLER)
 	u32 intf_type;
 	int ret;
 
-	if (!vdev->v4l2_dev->mdev)
+	/* Memory-to-memory devices are more complex and use
+	 * their own function to register its mc entities.
+	 */
+	if (!vdev->v4l2_dev->mdev || vdev->vfl_dir == VFL_DIR_M2M)
 		return 0;
 
 	vdev->entity.obj_type = MEDIA_ENTITY_TYPE_VIDEO_DEVICE;
 	vdev->entity.function = MEDIA_ENT_F_UNKNOWN;
 
-	switch (type) {
+	switch (vdev->vfl_type) {
 	case VFL_TYPE_GRABBER:
 		intf_type = MEDIA_INTF_T_V4L_VIDEO;
 		vdev->entity.function = MEDIA_ENT_F_IO_V4L;
@@ -994,7 +997,7 @@ int __video_register_device(struct video_device *vdev,
 	v4l2_device_get(vdev->v4l2_dev);
 
 	/* Part 5: Register the entity. */
-	ret = video_register_media_controller(vdev, type);
+	ret = video_register_media_controller(vdev);
 
 	/* Part 6: Activate this minor. The char device can now be used. */
 	set_bit(V4L2_FL_REGISTERED, &vdev->flags);