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[media] media: Entity use count

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Due to the wide differences between drivers regarding power management
needs, the media controller does not implement power management.
However, the media_entity structure includes a use_count field that
media drivers can use to track the number of users of every entity for
power management needs.

The use_count field is owned by media drivers and must not be touched by
entity drivers. Access to the field must be protected by the media
device graph_mutex lock.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Laurent Pinchart
2010-03-07 15:04:59 -03:00
committed by Mauro Carvalho Chehab
parent a5ccc48a7c
commit 503c3d829e
5 changed files with 73 additions and 0 deletions
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drivers/media/media-device.c
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@ -73,6 +73,7 @@ int __must_check media_device_register(struct media_device *mdev)
mdev->entity_id = 1;
INIT_LIST_HEAD(&mdev->entities);
spin_lock_init(&mdev->lock);
mutex_init(&mdev->graph_mutex);
/* Register the device node. */
mdev->devnode.fops = &media_device_fops;