V4L2 devices are media entities. As such they need to inherit from (include) the media_entity structure.
When registering/unregistering the device, the media entity is automatically registered/unregistered. The entity is acquired on device open and released on device close.
Signed-off-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Sakari Ailus sakari.ailus@iki.fi --- Documentation/video4linux/v4l2-framework.txt | 38 ++++++++++++++++++-- drivers/media/video/v4l2-dev.c | 49 +++++++++++++++++++++++-- include/media/v4l2-dev.h | 7 ++++ 3 files changed, 87 insertions(+), 7 deletions(-)
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt index 7de55cf..0627081 100644 --- a/Documentation/video4linux/v4l2-framework.txt +++ b/Documentation/video4linux/v4l2-framework.txt @@ -71,6 +71,10 @@ sub-device instances, the video_device struct stores V4L2 device node data and in the future a v4l2_fh struct will keep track of filehandle instances (this is not yet implemented).
+The V4L2 framework also optionally integrates with the media framework. If a +driver sets the struct v4l2_device mdev field, sub-devices and video nodes +will automatically appear in the media framework as entities. +
struct v4l2_device ------------------ @@ -84,11 +88,14 @@ You must register the device instance: v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev);
Registration will initialize the v4l2_device struct. If the dev->driver_data -field is NULL, it will be linked to v4l2_dev. Drivers that use the media -device framework in addition to the V4L2 framework need to set +field is NULL, it will be linked to v4l2_dev. + +Drivers that want integration with the media device framework need to set dev->driver_data manually to point to the driver-specific device structure that embed the struct v4l2_device instance. This is achieved by a -dev_set_drvdata() call before registering the V4L2 device instance. +dev_set_drvdata() call before registering the V4L2 device instance. They must +also set the struct v4l2_device mdev field to point to a properly initialized +and registered media_device instance.
If v4l2_dev->name is empty then it will be set to a value derived from dev (driver name followed by the bus_id, to be precise). If you set it up before @@ -530,6 +537,21 @@ If you use v4l2_ioctl_ops, then you should set either .unlocked_ioctl or The v4l2_file_operations struct is a subset of file_operations. The main difference is that the inode argument is omitted since it is never used.
+If integration with the media framework is needed, you must initialize the +media_entity struct embedded in the video_device struct (entity field) by +calling media_entity_init(): + + struct media_pad *pad = &my_vdev->pad; + int err; + + err = media_entity_init(&vdev->entity, 1, pad, 0); + +The pads array must have been previously initialized. There is no need to +manually set the struct media_entity type and name fields. + +A reference to the entity will be automatically acquired/released when the +video device is opened/closed. + v4l2_file_operations and locking --------------------------------
@@ -559,6 +581,9 @@ for you. return err; }
+If the v4l2_device parent device has a non-NULL mdev field, the video device +entity will be automatically registered with the media device. + Which device is registered depends on the type argument. The following types exist:
@@ -634,6 +659,13 @@ release, of course) will return an error as well. When the last user of the video device node exits, then the vdev->release() callback is called and you can do the final cleanup there.
+Don't forget to cleanup the media entity associated with the video device if +it has been initialized: + + media_entity_cleanup(&vdev->entity); + +This can be done from the release callback. +
video_device helper functions ----------------------------- diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c index abe04ef..e405b80 100644 --- a/drivers/media/video/v4l2-dev.c +++ b/drivers/media/video/v4l2-dev.c @@ -303,6 +303,9 @@ static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm) static int v4l2_open(struct inode *inode, struct file *filp) { struct video_device *vdev; +#if defined(CONFIG_MEDIA_CONTROLLER) + struct media_entity *entity = NULL; +#endif int ret = 0;
/* Check if the video device is available */ @@ -316,6 +319,16 @@ static int v4l2_open(struct inode *inode, struct file *filp) /* and increase the device refcount */ video_get(vdev); mutex_unlock(&videodev_lock); +#if defined(CONFIG_MEDIA_CONTROLLER) + if (vdev->v4l2_dev && vdev->v4l2_dev->mdev) { + entity = media_entity_get(&vdev->entity); + if (!entity) { + ret = -EBUSY; + video_put(vdev); + return ret; + } + } +#endif if (vdev->fops->open) { if (vdev->lock && mutex_lock_interruptible(vdev->lock)) { ret = -ERESTARTSYS; @@ -331,8 +344,13 @@ static int v4l2_open(struct inode *inode, struct file *filp)
err: /* decrease the refcount in case of an error */ - if (ret) + if (ret) { +#if defined(CONFIG_MEDIA_CONTROLLER) + if (vdev->v4l2_dev && vdev->v4l2_dev->mdev) + media_entity_put(entity); +#endif video_put(vdev); + } return ret; }
@@ -349,7 +367,10 @@ static int v4l2_release(struct inode *inode, struct file *filp) if (vdev->lock) mutex_unlock(vdev->lock); } - +#if defined(CONFIG_MEDIA_CONTROLLER) + if (vdev->v4l2_dev && vdev->v4l2_dev->mdev) + media_entity_put(&vdev->entity); +#endif /* decrease the refcount unconditionally since the release() return value is ignored. */ video_put(vdev); @@ -585,12 +606,27 @@ int __video_register_device(struct video_device *vdev, int type, int nr, if (nr != -1 && nr != vdev->num && warn_if_nr_in_use) printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__, name_base, nr, video_device_node_name(vdev)); - - /* Part 5: Activate this minor. The char device can now be used. */ +#if defined(CONFIG_MEDIA_CONTROLLER) + /* Part 5: Register the entity. */ + if (vdev->v4l2_dev && vdev->v4l2_dev->mdev) { + vdev->entity.type = MEDIA_ENT_T_DEVNODE_V4L; + vdev->entity.name = vdev->name; + vdev->entity.v4l.major = VIDEO_MAJOR; + vdev->entity.v4l.minor = vdev->minor; + ret = media_device_register_entity(vdev->v4l2_dev->mdev, + &vdev->entity); + if (ret < 0) + printk(KERN_WARNING + "%s: media_device_register_entity failed\n", + __func__); + } +#endif + /* Part 6: Activate this minor. The char device can now be used. */ set_bit(V4L2_FL_REGISTERED, &vdev->flags); mutex_lock(&videodev_lock); video_device[vdev->minor] = vdev; mutex_unlock(&videodev_lock); + return 0;
cleanup: @@ -618,6 +654,11 @@ void video_unregister_device(struct video_device *vdev) if (!vdev || !video_is_registered(vdev)) return;
+#if defined(CONFIG_MEDIA_CONTROLLER) + if (vdev->v4l2_dev && vdev->v4l2_dev->mdev) + media_device_unregister_entity(&vdev->entity); +#endif + mutex_lock(&videodev_lock); /* This must be in a critical section to prevent a race with v4l2_open. * Once this bit has been cleared video_get may never be called again. diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h index 4fe6831..51b2c51 100644 --- a/include/media/v4l2-dev.h +++ b/include/media/v4l2-dev.h @@ -16,6 +16,8 @@ #include <linux/mutex.h> #include <linux/videodev2.h>
+#include <media/media-entity.h> + #define VIDEO_MAJOR 81
#define VFL_TYPE_GRABBER 0 @@ -55,6 +57,9 @@ struct v4l2_file_operations {
struct video_device { +#if defined(CONFIG_MEDIA_CONTROLLER) + struct media_entity entity; +#endif /* device ops */ const struct v4l2_file_operations *fops;
@@ -100,6 +105,8 @@ struct video_device struct mutex *lock; };
+#define media_entity_to_video_device(entity) \ + container_of(entity, struct video_device, entity) /* dev to video-device */ #define to_video_device(cd) container_of(cd, struct video_device, dev)