As the struct media_device embeds struct media_devnode, the lifetime of
that object must be that same than that of the media_device.
References are obtained by media_entity_get() and released by
media_entity_put(). In case a driver uses media_device_alloc() to allocate
its media device, it must release the media device by calling
media_device_put() rather than media_device_cleanup().
Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
drivers/media/media-device.c | 13 +++++++++++++
include/media/media-device.h | 31 +++++++++++++++++++++++++++++++
2 files changed, 44 insertions(+)
diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 0920c02..e9f6e76 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -712,6 +712,17 @@ void media_device_init(struct media_device *mdev)
}
EXPORT_SYMBOL_GPL(media_device_init);
+static void media_device_release(struct media_devnode *devnode)
+{
+ struct media_device *mdev = to_media_device(devnode);
+
+ dev_dbg(devnode->parent, "Media device released\n");
+
+ media_device_cleanup(mdev);
+
+ kfree(mdev);
+}
+
struct media_device *media_device_alloc(struct device *dev)
{
struct media_device *mdev;
@@ -723,6 +734,8 @@ struct media_device *media_device_alloc(struct device *dev)
mdev->dev = dev;
media_device_init(mdev);
+ mdev->devnode.release = media_device_release;
+
return mdev;
}
EXPORT_SYMBOL_GPL(media_device_alloc);
diff --git a/include/media/media-device.h b/include/media/media-device.h
index c9b5798..fc0d82a 100644
--- a/include/media/media-device.h
+++ b/include/media/media-device.h
@@ -212,10 +212,39 @@ void media_device_init(struct media_device *mdev);
* @dev: The associated struct device pointer
*
* Allocate and initialise a media device. Returns a media device.
+ * The media device is refcounted, and this function returns a media
+ * device the refcount of which is one (1).
+ *
+ * References are taken and given using media_device_get() and
+ * media_device_put().
*/
struct media_device *media_device_alloc(struct device *dev);
/**
+ * media_device_get() - Get a reference to a media device
+ *
+ * mdev: media device
+ */
+#define media_device_get(mdev) \
+ do { \
+ dev_dbg((mdev)->dev, "%s: get media device %s\n", \
+ __func__, (mdev)->bus_info); \
+ get_device(&(mdev)->devnode.dev); \
+ } while (0)
+
+/**
+ * media_device_put() - Put a reference to a media device
+ *
+ * mdev: media device
+ */
+#define media_device_put(mdev) \
+ do { \
+ dev_dbg((mdev)->dev, "%s: put media device %s\n", \
+ __func__, (mdev)->bus_info); \
+ put_device(&(mdev)->devnode.dev); \
+ } while (0)
+
+/**
* media_device_cleanup() - Cleanups a media device element
*
* @mdev: pointer to struct &media_device
@@ -464,6 +493,8 @@ static inline struct media_device *media_device_alloc(struct device *dev)
{
return NULL;
}
+#define media_device_get(mdev) do { } while (0)
+#define media_device_put(mdev) do { } while (0)
static inline int media_device_register(struct media_device *mdev)
{
return 0;
--
2.1.4
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