On 26/09/17 00:25, Sakari Ailus wrote:
> Registering a notifier has required the knowledge of struct v4l2_device
> for the reason that sub-devices generally are registered to the
> v4l2_device (as well as the media device, also available through
> v4l2_device).
>
> This information is not available for sub-device drivers at probe time.
>
> What this patch does is that it allows registering notifiers without
> having v4l2_device around. Instead the sub-device pointer is stored in the
> notifier. Once the sub-device of the driver that registered the notifier
> is registered, the notifier will gain the knowledge of the v4l2_device,
> and the binding of async sub-devices from the sub-device driver's notifier
> may proceed.
>
> The root notifier's complete callback is only called when all sub-device
> notifiers are completed.
>
> Signed-off-by: Sakari Ailus <sakari.ai...@linux.intel.com>
Acked-by: Hans Verkuil <hans.verk...@cisco.com>
> ---
> drivers/media/v4l2-core/v4l2-async.c | 218
> +++++++++++++++++++++++++++++------
> include/media/v4l2-async.h | 16 ++-
> 2 files changed, 199 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-async.c
> b/drivers/media/v4l2-core/v4l2-async.c
> index 1d4132305243..735f72f81740 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -124,11 +124,109 @@ static struct v4l2_async_subdev *v4l2_async_find_match(
> return NULL;
> }
>
> +/* Find the sub-device notifier registered by a sub-device driver. */
> +static struct v4l2_async_notifier *v4l2_async_find_subdev_notifier(
> + struct v4l2_subdev *sd)
> +{
> + struct v4l2_async_notifier *n;
> +
> + list_for_each_entry(n, ¬ifier_list, list)
> + if (n->sd == sd)
> + return n;
> +
> + return NULL;
> +}
> +
> +/* Get v4l2_device related to the notifier if one can be found. */
> +static struct v4l2_device *v4l2_async_notifier_find_v4l2_dev(
> + struct v4l2_async_notifier *notifier)
> +{
> + while (notifier->parent)
> + notifier = notifier->parent;
> +
> + return notifier->v4l2_dev;
> +}
> +
> +/*
> + * Return true if all child sub-device notifiers are complete, false
> otherwise.
> + */
> +static bool v4l2_async_notifier_can_complete(
> + struct v4l2_async_notifier *notifier)
> +{
> + struct v4l2_subdev *sd;
> +
> + if (!list_empty(¬ifier->waiting))
> + return false;
> +
> + list_for_each_entry(sd, ¬ifier->done, async_list) {
> + struct v4l2_async_notifier *subdev_notifier =
> + v4l2_async_find_subdev_notifier(sd);
> +
> + if (subdev_notifier &&
> + !v4l2_async_notifier_can_complete(subdev_notifier))
> + return false;
> + }
> +
> + return true;
> +}
> +
> +/* Complete all notifiers. Call on the root notifier. */
> +static int v4l2_async_notifier_complete(
> + struct v4l2_async_notifier *notifier)
> +{
> + struct v4l2_subdev *sd;
> +
> + list_for_each_entry(sd, ¬ifier->done, async_list) {
> + struct v4l2_async_notifier *subdev_notifier =
> + v4l2_async_find_subdev_notifier(sd);
> + int ret;
> +
> + if (!subdev_notifier)
> + continue;
> +
> + ret = v4l2_async_notifier_complete(subdev_notifier);
> + if (ret)
> + return ret;
> + }
> +
> + return v4l2_async_notifier_call_complete(notifier);
> +}
> +
> +/*
> + * Complete notifiers if possible. This is done when all async sub-devices
> have
> + * been bound; v4l2_device is also available then.
> + */
> +static int v4l2_async_notifier_try_complete(
> + struct v4l2_async_notifier *notifier)
> +{
> + /* Quick check whether there are still more sub-devices here. */
> + if (!list_empty(¬ifier->waiting))
> + return 0;
> +
> + /* Check the entire notifier tree; find the root notifier first. */
> + while (notifier->parent)
> + notifier = notifier->parent;
> +
> + /* This is root if it has v4l2_dev. */
> + if (!notifier->v4l2_dev)
> + return 0;
> +
> + /* Is everything ready? */
> + if (!v4l2_async_notifier_can_complete(notifier))
> + return 0;
> +
> + return v4l2_async_notifier_complete(notifier);
> +}
> +
> +static int v4l2_async_notifier_try_all_subdevs(
> + struct v4l2_async_notifier *notifier);
> +
> static int v4l2_async_match_notify(struct v4l2_async_notifier *notifier,
> struct v4l2_device *v4l2_dev,
> struct v4l2_subdev *sd,
> struct v4l2_async_subdev *asd)
> {
> + struct v4l2_async_notifier *subdev_notifier;
> int ret;
>
> ret = v4l2_device_register_subdev(v4l2_dev, sd);
> @@ -149,8 +247,17 @@ static int v4l2_async_match_notify(struct
> v4l2_async_notifier *notifier,
> /* Move from the global subdevice list to notifier's done */
> list_move(&sd->async_list, ¬ifier->done);
>
> - if (list_empty(¬ifier->waiting))
> - return v4l2_async_notifier_call_complete(notifier);
> + /*
> + * See if the sub-device has a notifier. If it does, proceed
> + * with checking for its async sub-devices.
> + */
> + subdev_notifier = v4l2_async_find_subdev_notifier(sd);
> + if (subdev_notifier && !subdev_notifier->parent) {
> + subdev_notifier->parent = notifier;
> + ret = v4l2_async_notifier_try_all_subdevs(subdev_notifier);
> + if (ret)
> + return ret;
> + }
>
> return 0;
> }
> @@ -159,10 +266,15 @@ static int v4l2_async_match_notify(struct
> v4l2_async_notifier *notifier,
> static int v4l2_async_notifier_try_all_subdevs(
> struct v4l2_async_notifier *notifier)
> {
> - struct v4l2_device *v4l2_dev = notifier->v4l2_dev;
> - struct v4l2_subdev *sd, *tmp;
> + struct v4l2_device *v4l2_dev =
> + v4l2_async_notifier_find_v4l2_dev(notifier);
> + struct v4l2_subdev *sd;
>
> - list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
> + if (!v4l2_dev)
> + return 0;
> +
> +again:
> + list_for_each_entry(sd, &subdev_list, async_list) {
> struct v4l2_async_subdev *asd;
> int ret;
>
> @@ -171,10 +283,16 @@ static int v4l2_async_notifier_try_all_subdevs(
> continue;
>
> ret = v4l2_async_match_notify(notifier, v4l2_dev, sd, asd);
> - if (ret < 0) {
> - mutex_unlock(&list_lock);
> + if (ret < 0)
> return ret;
> - }
> +
> + /*
> + * v4l2_async_match_notify() may lead to registering a
> + * new notifier and thus changing the async subdevs
> + * list. In order to proceed safely from here, restart
> + * parsing the list from the beginning.
> + */
> + goto again;
> }
>
> return 0;
> @@ -201,15 +319,6 @@ static int __v4l2_async_notifier_register(struct
> v4l2_async_notifier *notifier)
> INIT_LIST_HEAD(¬ifier->waiting);
> INIT_LIST_HEAD(¬ifier->done);
>
> - if (!notifier->num_subdevs) {
> - int ret;
> -
> - ret = v4l2_async_notifier_call_complete(notifier);
> - notifier->v4l2_dev = NULL;
> -
> - return ret;
> - }
> -
> for (i = 0; i < notifier->num_subdevs; i++) {
> asd = notifier->subdevs[i];
>
> @@ -236,18 +345,20 @@ static int __v4l2_async_notifier_register(struct
> v4l2_async_notifier *notifier)
> return ret;
> }
>
> + ret = v4l2_async_notifier_try_complete(notifier);
> +
> /* Keep also completed notifiers on the list */
> list_add(¬ifier->list, ¬ifier_list);
>
> mutex_unlock(&list_lock);
>
> - return 0;
> + return ret;
> }
>
> int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> struct v4l2_async_notifier *notifier)
> {
> - if (WARN_ON(!v4l2_dev))
> + if (WARN_ON(!v4l2_dev || notifier->sd))
> return -EINVAL;
>
> notifier->v4l2_dev = v4l2_dev;
> @@ -256,18 +367,31 @@ int v4l2_async_notifier_register(struct v4l2_device
> *v4l2_dev,
> }
> EXPORT_SYMBOL(v4l2_async_notifier_register);
>
> -void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
> +int v4l2_async_subdev_notifier_register(struct v4l2_subdev *sd,
> + struct v4l2_async_notifier *notifier)
> {
> - struct v4l2_subdev *sd, *tmp;
> + if (WARN_ON(!sd || notifier->v4l2_dev))
> + return -EINVAL;
>
> - if (!notifier->v4l2_dev)
> - return;
> + notifier->sd = sd;
>
> - mutex_lock(&list_lock);
> + return __v4l2_async_notifier_register(notifier);
> +}
> +EXPORT_SYMBOL(v4l2_async_subdev_notifier_register);
>
> - list_del(¬ifier->list);
> +/* Unbind all sub-devices in the notifier tree. */
> +static void v4l2_async_notifier_unbind_all_subdevs(
> + struct v4l2_async_notifier *notifier)
> +{
> + struct v4l2_subdev *sd, *tmp;
>
> list_for_each_entry_safe(sd, tmp, ¬ifier->done, async_list) {
> + struct v4l2_async_notifier *subdev_notifier =
> + v4l2_async_find_subdev_notifier(sd);
> +
> + if (subdev_notifier)
> + v4l2_async_notifier_unbind_all_subdevs(subdev_notifier);
> +
> v4l2_async_cleanup(sd);
>
> v4l2_async_notifier_call_unbind(notifier, sd, sd->asd);
> @@ -275,9 +399,24 @@ void v4l2_async_notifier_unregister(struct
> v4l2_async_notifier *notifier)
> list_move(&sd->async_list, &subdev_list);
> }
>
> - mutex_unlock(&list_lock);
> + notifier->parent = NULL;
> +}
>
> +void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
> +{
> + if (!notifier->v4l2_dev && !notifier->sd)
> + return;
> +
> + mutex_lock(&list_lock);
> +
> + v4l2_async_notifier_unbind_all_subdevs(notifier);
> +
> + notifier->sd = NULL;
> notifier->v4l2_dev = NULL;
> +
> + list_del(¬ifier->list);
> +
> + mutex_unlock(&list_lock);
> }
> EXPORT_SYMBOL(v4l2_async_notifier_unregister);
>
> @@ -327,14 +466,25 @@ int v4l2_async_register_subdev(struct v4l2_subdev *sd)
> INIT_LIST_HEAD(&sd->async_list);
>
> list_for_each_entry(notifier, ¬ifier_list, list) {
> - struct v4l2_async_subdev *asd = v4l2_async_find_match(notifier,
> - sd);
> - if (asd) {
> - int ret = v4l2_async_match_notify(
> - notifier, notifier->v4l2_dev, sd, asd);
> - mutex_unlock(&list_lock);
> - return ret;
> - }
> + struct v4l2_device *v4l2_dev =
> + v4l2_async_notifier_find_v4l2_dev(notifier);
> + struct v4l2_async_subdev *asd;
> + int ret;
> +
> + if (!v4l2_dev)
> + continue;
> +
> + asd = v4l2_async_find_match(notifier, sd);
> + if (!asd)
> + continue;
> +
> + ret = v4l2_async_match_notify(notifier, v4l2_dev, sd, asd);
> +
> + if (!ret)
> + ret = v4l2_async_notifier_try_complete(notifier);
> +
> + mutex_unlock(&list_lock);
> + return ret;
> }
>
> /* None matched, wait for hot-plugging */
> diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> index 7d56c355138b..0b30a631ad19 100644
> --- a/include/media/v4l2-async.h
> +++ b/include/media/v4l2-async.h
> @@ -102,7 +102,9 @@ struct v4l2_async_notifier_operations {
> * @num_subdevs: number of subdevices used in the subdevs array
> * @max_subdevs: number of subdevices allocated in the subdevs array
> * @subdevs: array of pointers to subdevice descriptors
> - * @v4l2_dev: pointer to struct v4l2_device
> + * @v4l2_dev: v4l2_device of the root notifier, NULL otherwise
> + * @sd: sub-device that registered the notifier, NULL otherwise
> + * @parent: parent notifier
> * @waiting: list of struct v4l2_async_subdev, waiting for their drivers
> * @done: list of struct v4l2_subdev, already probed
> * @list: member in a global list of notifiers
> @@ -113,6 +115,8 @@ struct v4l2_async_notifier {
> unsigned int max_subdevs;
> struct v4l2_async_subdev **subdevs;
> struct v4l2_device *v4l2_dev;
> + struct v4l2_subdev *sd;
> + struct v4l2_async_notifier *parent;
> struct list_head waiting;
> struct list_head done;
> struct list_head list;
> @@ -128,6 +132,16 @@ int v4l2_async_notifier_register(struct v4l2_device
> *v4l2_dev,
> struct v4l2_async_notifier *notifier);
>
> /**
> + * v4l2_async_subdev_notifier_register - registers a subdevice asynchronous
> + * notifier for a sub-device
> + *
> + * @sd: pointer to &struct v4l2_subdev
> + * @notifier: pointer to &struct v4l2_async_notifier
> + */
> +int v4l2_async_subdev_notifier_register(struct v4l2_subdev *sd,
> + struct v4l2_async_notifier *notifier);
> +
> +/**
> * v4l2_async_notifier_unregister - unregisters a subdevice asynchronous
> notifier
> *
> * @notifier: pointer to &struct v4l2_async_notifier
>
