Re: [PATCH RFC v2 3/3] media: added managed v4l2 subdevice initialization

Hans Verkuil
2013-05-13T09:24:38Z

Hi Andrzej,

On Mon May 13 2013 10:34:46 Andrzej Hajda wrote:
> This patch adds managed versions of initialization
> functions for v4l2 subdevices.

I figured out what is bothering me about this patch: the fact that it is
tied to the v4l2_i2c_subdev_init/v4l2_subdev_init functions. Normally devm
functions are wrappers around functions that actually allocate some resource.
That's not the case with these subdev_init functions, they just initialize
fields in a struct.

Why not drop those wrappers and just provide the devm_v4l2_subdev_bind
function? That's actually the one that is doing the binding, and is a function
drivers can call explicitly.

The only thing you need to add to devm_v4l2_subdev_bind is a WARN_ON check that
sd->ops != NULL, verifying that v4l2_subdev_init was called before the
bind().

I would be much happier with that solution.

Regards,

Hans

>
> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
> Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
> v2:
> - changes of v4l2-ctrls.h moved to proper patch
> ---
> drivers/media/v4l2-core/v4l2-common.c | 10 +++++++
> drivers/media/v4l2-core/v4l2-subdev.c | 52 +++++++++++++++++++++++++++++++++
> include/media/v4l2-common.h | 2 ++
> include/media/v4l2-subdev.h | 5 ++++
> 4 files changed, 69 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
> index 3fed63f..96aac931 100644
> --- a/drivers/media/v4l2-core/v4l2-common.c
> +++ b/drivers/media/v4l2-core/v4l2-common.c
> @@ -301,7 +301,17 @@ void v4l2_i2c_subdev_init(struct v4l2_subdev *sd, struct i2c_client *client,
> }
> EXPORT_SYMBOL_GPL(v4l2_i2c_subdev_init);
>
> +int devm_v4l2_i2c_subdev_init(struct v4l2_subdev *sd, struct i2c_client *client,
> + const struct v4l2_subdev_ops *ops)
> +{
> + int ret;
>
> + ret = devm_v4l2_subdev_bind(&client->dev, sd);
> + if (!ret)
> + v4l2_i2c_subdev_init(sd, client, ops);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(devm_v4l2_i2c_subdev_init);
>
> /* Load an i2c sub-device. */
> struct v4l2_subdev *v4l2_i2c_new_subdev_board(struct v4l2_device *v4l2_dev,
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 996c248..87ce2f6 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -474,3 +474,55 @@ void v4l2_subdev_init(struct v4l2_subdev *sd, const struct v4l2_subdev_ops *ops)
> #endif
> }
> EXPORT_SYMBOL(v4l2_subdev_init);
> +
> +static void devm_v4l2_subdev_release(struct device *dev, void *res)
> +{
> + struct v4l2_subdev **sd = res;
> +
> + v4l2_device_unregister_subdev(*sd);
> +#if defined(CONFIG_MEDIA_CONTROLLER)
> + media_entity_cleanup(&(*sd)->entity);
> +#endif
> +}
> +
> +int devm_v4l2_subdev_bind(struct device *dev, struct v4l2_subdev *sd)
> +{
> + struct v4l2_subdev **dr;
> +
> + dr = devres_alloc(devm_v4l2_subdev_release, sizeof(*dr), GFP_KERNEL);
> + if (!dr)
> + return -ENOMEM;
> +
> + *dr = sd;
> + devres_add(dev, dr);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(devm_v4l2_subdev_bind);
> +
> +int devm_v4l2_subdev_init(struct device *dev, struct v4l2_subdev *sd,
> + const struct v4l2_subdev_ops *ops)
> +{
> + int ret;
> +
> + ret = devm_v4l2_subdev_bind(dev, sd);
> + if (!ret)
> + v4l2_subdev_init(sd, ops);
> + return ret;
> +}
> +EXPORT_SYMBOL(devm_v4l2_subdev_init);
> +
> +static int devm_v4l2_subdev_match(struct device *dev, void *res,
> + void *data)
> +{
> + struct v4l2_subdev **this = res, **sd = data;
> +
> + return *this == *sd;
> +}
> +
> +void devm_v4l2_subdev_free(struct device *dev, struct v4l2_subdev *sd)
> +{
> + WARN_ON(devres_release(dev, devm_v4l2_subdev_release,
> + devm_v4l2_subdev_match, &sd));
> +}
> +EXPORT_SYMBOL_GPL(devm_v4l2_subdev_free);
> diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
> index 1d93c48..da62e2b 100644
> --- a/include/media/v4l2-common.h
> +++ b/include/media/v4l2-common.h
> @@ -136,6 +136,8 @@ struct v4l2_subdev *v4l2_i2c_new_subdev_board(struct v4l2_device *v4l2_dev,
> /* Initialize a v4l2_subdev with data from an i2c_client struct */
> void v4l2_i2c_subdev_init(struct v4l2_subdev *sd, struct i2c_client *client,
> const struct v4l2_subdev_ops *ops);
> +int devm_v4l2_i2c_subdev_init(struct v4l2_subdev *sd, struct i2c_client *client,
> + const struct v4l2_subdev_ops *ops);
> /* Return i2c client address of v4l2_subdev. */
> unsigned short v4l2_i2c_subdev_addr(struct v4l2_subdev *sd);
>
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index 5298d67..881abdd 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -657,6 +657,11 @@ int v4l2_subdev_link_validate(struct media_link *link);
> void v4l2_subdev_init(struct v4l2_subdev *sd,
> const struct v4l2_subdev_ops *ops);
>
> +int devm_v4l2_subdev_bind(struct device *dev, struct v4l2_subdev *sd);
> +int devm_v4l2_subdev_init(struct device *dev, struct v4l2_subdev *sd,
> + const struct v4l2_subdev_ops *ops);
> +void devm_v4l2_subdev_free(struct device *dev, struct v4l2_subdev *sd);
> +
> /* Call an ops of a v4l2_subdev, doing the right checks against
> NULL pointers.
>
>