From: Hans Verkuil <hverkuil@xs4all.nl>
To: Shuah Khan <shuahkh@osg.samsung.com>,
mchehab@osg.samsung.com, laurent.pinchart@ideasonboard.com,
sakari.ailus@iki.fi, hans.verkuil@cisco.com,
chehabrafael@gmail.com, javier@osg.samsung.com,
inki.dae@samsung.com, g.liakhovetski@gmx.de,
jh1009.sung@samsung.com
Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] media: add media_device_unregister_put() interface
Date: Mon, 23 May 2016 13:39:06 +0200 [thread overview]
Message-ID: <5742EBDA.1010902@xs4all.nl> (raw)
In-Reply-To: <14efd8cc91d49e34936fd227d1208429d16e3fa0.1463158822.git.shuahkh@osg.samsung.com>
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@osg.samsung.com>
> ---
> 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)
> {
>
next prev parent reply other threads:[~2016-05-23 11:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-13 17:09 [PATCH 0/3] Media Device Allocator API Shuah Khan
2016-05-13 17:09 ` [PATCH 1/3] media: " Shuah Khan
2016-05-23 11:26 ` Hans Verkuil
2016-05-24 17:05 ` Shuah Khan
2016-05-13 17:09 ` [PATCH 2/3] media: add media_device_unregister_put() interface Shuah Khan
2016-05-23 11:39 ` Hans Verkuil [this message]
2016-05-24 17:13 ` Shuah Khan
2016-05-13 17:09 ` [PATCH 3/3] media: change au0828 to use Media Device Allocator API Shuah Khan
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