On 05/13/2016 07:09 PM, Shuah Khan wrote:
> Add media_device_unregister_put() interface to release reference to a media
> device allocated using the Media Device Allocator API. The media device is
> unregistered and freed when the last driver that holds the reference to the
> media device releases the reference. The media device is unregistered and
> freed in the kref put handler.
>
> Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
> ---
> drivers/media/media-device.c | 11 +++++++++++
> include/media/media-device.h | 15 +++++++++++++++
> 2 files changed, 26 insertions(+)
>
> diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
> index 33a9952..b5c279a 100644
> --- a/drivers/media/media-device.c
> +++ b/drivers/media/media-device.c
> @@ -36,6 +36,7 @@
> #include <media/media-device.h>
> #include <media/media-devnode.h>
> #include <media/media-entity.h>
> +#include <media/media-dev-allocator.h>
>
> #ifdef CONFIG_MEDIA_CONTROLLER
>
> @@ -818,6 +819,16 @@ void media_device_unregister(struct media_device *mdev)
> }
> EXPORT_SYMBOL_GPL(media_device_unregister);
>
> +void media_device_unregister_put(struct media_device *mdev)
> +{
> + if (mdev == NULL)
> + return;
> +
> + dev_dbg(mdev->dev, "%s: mdev %p\n", __func__, mdev);
> + media_device_put(mdev);
> +}
> +EXPORT_SYMBOL_GPL(media_device_unregister_put);
> +
I don't really see the need for a new unregister_put function. The only thing
it adds compared to media_device_put is the 'if (mdev == NULL)' check.
Is that check needed at all?
I would probably go for an API like this:
<brainstorm mode on>
/* Not sure if there should be a void *priv as the last argument */
int (*mdev_init_fnc)(struct media_device *mdev, struct device *dev);
/* Perhaps a void *priv is needed to pass to mdev_init_fnc?
The callback is there to initialize the media_device and it's called
with the lock held.
*/
struct media_device *media_device_allocate(struct device *dev, mdev_init_fnc fnc);
/* Helper function for usb devices */
struct media_device *media_device_usb_allocate(struct usb_device *udev,
char *driver_name);
/* counterpart of media_device_allocate, that makes more sense than allocate/put IMHO */
void media_device_release(struct media_device *mdev);
<brainstorm mode off>
Regards,
Hans
> static void media_device_release_devres(struct device *dev, void *res)
> {
> }
> diff --git a/include/media/media-device.h b/include/media/media-device.h
> index f743ae2..8bd836e 100644
> --- a/include/media/media-device.h
> +++ b/include/media/media-device.h
> @@ -499,6 +499,18 @@ int __must_check __media_device_register(struct media_device *mdev,
> void media_device_unregister(struct media_device *mdev);
>
> /**
> + * media_device_unregister_put() - Unregisters a media device element
> + *
> + * @mdev: pointer to struct &media_device
> + *
> + * Should be called to unregister media device allocated with Media Device
> + * Allocator API media_device_get() interface.
> + * It is safe to call this function on an unregistered (but initialised)
> + * media device.
> + */
> +void media_device_unregister_put(struct media_device *mdev);
> +
> +/**
> * media_device_register_entity() - registers a media entity inside a
> * previously registered media device.
> *
> @@ -658,6 +670,9 @@ static inline int media_device_register(struct media_device *mdev)
> static inline void media_device_unregister(struct media_device *mdev)
> {
> }
> +static inline void media_device_unregister_put(struct media_device *mdev)
> +{
> +}
> static inline int media_device_register_entity(struct media_device *mdev,
> struct media_entity *entity)
> {
>
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