[PATCH v8 10/12] v4l: Add a media_device pointer to the v4l2_device structure

From: Laurent Pinchart
Date: Thu Jan 27 2011 - 07:32:19 EST

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@xxxxxxxxxxxxxxxx>
Documentation/video4linux/v4l2-framework.txt | 17 ++++++++++++-----
drivers/media/video/v4l2-device.c | 13 +++++++------
include/media/v4l2-device.h | 4 ++++
3 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 4db1def..aeb2a22 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
diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index 97e84df..5c16a12 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -47,9 +47,8 @@ int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
if (!v4l2_dev->name[0])
snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %s",
dev->driver->name, dev_name(dev));
- if (dev_get_drvdata(dev))
- v4l2_warn(v4l2_dev, "Non-NULL drvdata on register\n");
- dev_set_drvdata(dev, v4l2_dev);
+ if (!dev_get_drvdata(dev))
+ dev_set_drvdata(dev, v4l2_dev);
return 0;
@@ -72,10 +71,12 @@ EXPORT_SYMBOL_GPL(v4l2_device_set_name);

void v4l2_device_disconnect(struct v4l2_device *v4l2_dev)
- if (v4l2_dev->dev) {
+ if (v4l2_dev->dev == NULL)
+ return;
+ if (dev_get_drvdata(v4l2_dev->dev) == v4l2_dev)
dev_set_drvdata(v4l2_dev->dev, NULL);
- v4l2_dev->dev = NULL;
- }
+ v4l2_dev->dev = NULL;

diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h
index b16f307..759db73 100644
--- a/include/media/v4l2-device.h
+++ b/include/media/v4l2-device.h
@@ -21,6 +21,7 @@
#ifndef _V4L2_DEVICE_H
#define _V4L2_DEVICE_H

+#include <media/media-device.h>
#include <media/v4l2-subdev.h>

/* Each instance of a V4L2 device should create the v4l2_device struct,
@@ -39,6 +40,9 @@ struct v4l2_device {
Note: dev might be NULL if there is no parent device
as is the case with e.g. ISA devices. */
struct device *dev;
+ struct media_device *mdev;
/* used to keep track of the registered subdevs */
struct list_head subdevs;
/* lock this struct; can be used by the driver as well if this

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