[media] v4l: Make video_device inherit from media_entity (2c0ab67b) · Commits · e / devices / android_kernel_teracube_2e

Documentation/video4linux/v4l2-framework.txt

+35 −3

Original line number	Diff line number	Diff line
		@@ -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
		-----------------------------

drivers/media/video/v4l2-dev.c

+45 −4

Original line number	Diff line number	Diff line
		@@ -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.

include/media/v4l2-dev.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -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)