path: root/drivers/media/media-device.c
diff options
authorJavier Martinez Canillas <javier@osg.samsung.com>2015-12-11 20:57:08 -0200
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>2016-01-11 12:19:15 -0200
commit9832e155f1ed3030fdfaa19e72c06472dc2ecb1d (patch)
treefe787b9bd8804b7094ba797897e77ed60077a5e3 /drivers/media/media-device.c
parent821ed3662913faca0653c201fa9e36fbab81f17c (diff)
[media] media-device: split media initialization and registration
The media device node is registered and so made visible to user-space before entities are registered and links created which means that the media graph obtained by user-space could be only partially enumerated if that happens too early before all the graph has been created. To avoid this race condition, split the media init and registration in separate functions and only register the media device node when all the pending subdevices have been registered, either explicitly by the driver or asynchronously using v4l2_async_register_subdev(). The media_device_register() had a check for drivers not filling dev and model fields but all drivers in mainline set them and not doing it will be a driver bug so change the function return to void and add a BUG_ON() for dev being NULL instead. Also, add a media_device_cleanup() function that will destroy the graph_mutex that is initialized in media_device_init(). [mchehab@osg.samsung.com: Fix compilation if !CONFIG_MEDIA_CONTROLLER and remove two warnings added by this changeset] Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com> Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Diffstat (limited to 'drivers/media/media-device.c')
1 files changed, 29 insertions, 8 deletions
diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 189c2ba8c3d3..b718c783debd 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -616,7 +616,7 @@ EXPORT_SYMBOL_GPL(media_device_unregister_entity);
- * media_device_register - register a media device
+ * media_device_init() - initialize a media device
* @mdev: The media device
* The caller is responsible for initializing the media device before
@@ -625,14 +625,8 @@ EXPORT_SYMBOL_GPL(media_device_unregister_entity);
* - dev must point to the parent device
* - model must be filled with the device model name
-int __must_check __media_device_register(struct media_device *mdev,
- struct module *owner)
+void media_device_init(struct media_device *mdev)
- int ret;
- if (WARN_ON(mdev->dev == NULL || mdev->model[0] == 0))
- return -EINVAL;
@@ -640,6 +634,33 @@ int __must_check __media_device_register(struct media_device *mdev,
+ dev_dbg(mdev->dev, "Media device initialized\n");
+ * media_device_cleanup() - Cleanup a media device
+ * @mdev: The media device
+ *
+ */
+void media_device_cleanup(struct media_device *mdev)
+ mutex_destroy(&mdev->graph_mutex);
+ * __media_device_register() - register a media device
+ * @mdev: The media device
+ * @owner: The module owner
+ *
+ * returns zero on success or a negative error code.
+ */
+int __must_check __media_device_register(struct media_device *mdev,
+ struct module *owner)
+ int ret;
/* Register the device node. */
mdev->devnode.fops = &media_device_fops;
mdev->devnode.parent = mdev->dev;

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