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| author | Laurent Pinchart <laurent.pinchart@ideasonboard.com> | 2009-12-09 14:40:05 +0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2011-03-22 10:53:18 +0300 |
| commit | 95db3a60e0652a52df145aacade1a88c5acef659 (patch) | |
| tree | 7b8a14a964684ecd49667125e5429360e41c11d5 /Documentation | |
| parent | e02188c90f6ef61f0844c42508fe603c5d4fa42b (diff) | |
| download | linux-95db3a60e0652a52df145aacade1a88c5acef659.tar.xz | |
[media] v4l: Add a media_device pointer to the v4l2_device structure
The pointer will later be used to register/unregister media entities
when registering/unregistering a v4l2_subdev or a video_device.
With the introduction of media devices, device drivers need to store a
pointer to a driver-specific structure in the device's drvdata.
v4l2_device can't claim ownership of the drvdata anymore.
To maintain compatibility with drivers that rely on v4l2_device storing
a pointer to itself in the device's drvdata, v4l2_device_register() will
keep doing so if the drvdata is NULL.
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>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/video4linux/v4l2-framework.txt | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt index eb8479565dc4..7de55cfae04e 100644 --- a/Documentation/video4linux/v4l2-framework.txt +++ b/Documentation/video4linux/v4l2-framework.txt @@ -83,11 +83,17 @@ You must register the device instance: v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev); -Registration will initialize the v4l2_device struct and link dev->driver_data -to v4l2_dev. 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 calling v4l2_device_register then it will be untouched. If dev is -NULL, then you *must* setup v4l2_dev->name before calling v4l2_device_register. +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 +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. + +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 +calling v4l2_device_register then it will be untouched. If dev is NULL, then +you *must* setup v4l2_dev->name before calling v4l2_device_register. You can use v4l2_device_set_name() to set the name based on a driver name and a driver-global atomic_t instance. This will generate names like ivtv0, ivtv1, @@ -108,6 +114,7 @@ You unregister with: v4l2_device_unregister(struct v4l2_device *v4l2_dev); +If the dev->driver_data field points to v4l2_dev, it will be reset to NULL. Unregistering will also automatically unregister all subdevs from the device. If you have a hotpluggable device (e.g. a USB device), then when a disconnect |