On 2017-10-27 11:27:09 +0300, 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 complete callback of the root notifier will be called only when the
> v4l2_device is available and no notifier has pending sub-devices to bind.
> No complete callbacks are supported for sub-device notifiers.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> Acked-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Acked-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> ---
> drivers/media/v4l2-core/v4l2-async.c | 212 ++++++++++++++++++++++++++++-------
> include/media/v4l2-async.h | 19 +++-
> 2 files changed, 189 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> index 6265717769d2..ed539c4fd5dc 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -124,11 +124,87 @@ 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 the master notifier 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_call_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);
> @@ -149,17 +225,36 @@ 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);
>
> - return 0;
> + /*
> + * See if the sub-device has a notifier. If not, return here.
> + */
> + subdev_notifier = v4l2_async_find_subdev_notifier(sd);
> + if (!subdev_notifier || subdev_notifier->parent)
> + return 0;
> +
> + /*
> + * Proceed with checking for the sub-device notifier's async
> + * sub-devices, and return the result. The error will be handled by the
> + * caller.
> + */
> + subdev_notifier->parent = notifier;
> +
> + return v4l2_async_notifier_try_all_subdevs(subdev_notifier);
> }
>
> /* Test all async sub-devices in a notifier for a match. */
> 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;
> +
> + if (!v4l2_dev)
> + return 0;
>
> - list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
> +again:
> + list_for_each_entry(sd, &subdev_list, async_list) {
> struct v4l2_async_subdev *asd;
> int ret;
>
> @@ -170,6 +265,14 @@ static int v4l2_async_notifier_try_all_subdevs(
> ret = v4l2_async_match_notify(notifier, v4l2_dev, sd, asd);
> 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;
> @@ -183,17 +286,26 @@ static void v4l2_async_cleanup(struct v4l2_subdev *sd)
> sd->asd = NULL;
> }
>
> +/* 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_notifier_call_unbind(notifier, sd, sd->asd);
> v4l2_async_cleanup(sd);
>
> list_move(&sd->async_list, &subdev_list);
> }
> +
> + notifier->parent = NULL;
> }
>
> static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> @@ -208,15 +320,6 @@ 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];
>
> @@ -238,16 +341,12 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> mutex_lock(&list_lock);
>
> ret = v4l2_async_notifier_try_all_subdevs(notifier);
> - if (ret) {
> - mutex_unlock(&list_lock);
> - return ret;
> - }
> + if (ret)
> + goto err_unbind;
>
> - if (list_empty(¬ifier->waiting)) {
> - ret = v4l2_async_notifier_call_complete(notifier);
> - if (ret)
> - goto err_complete;
> - }
> + ret = v4l2_async_notifier_try_complete(notifier);
> + if (ret)
> + goto err_unbind;
>
> /* Keep also completed notifiers on the list */
> list_add(¬ifier->list, ¬ifier_list);
> @@ -256,7 +355,10 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
>
> return 0;
>
> -err_complete:
> +err_unbind:
> + /*
> + * On failure, unbind all sub-devices registered through this notifier.
> + */
> v4l2_async_notifier_unbind_all_subdevs(notifier);
>
> mutex_unlock(&list_lock);
> @@ -269,7 +371,7 @@ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> {
> int ret;
>
> - if (WARN_ON(!v4l2_dev))
> + if (WARN_ON(!v4l2_dev || notifier->sd))
> return -EINVAL;
>
> notifier->v4l2_dev = v4l2_dev;
> @@ -282,20 +384,39 @@ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> }
> EXPORT_SYMBOL(v4l2_async_notifier_register);
>
> +int v4l2_async_subdev_notifier_register(struct v4l2_subdev *sd,
> + struct v4l2_async_notifier *notifier)
> +{
> + int ret;
> +
> + if (WARN_ON(!sd || notifier->v4l2_dev))
> + return -EINVAL;
> +
> + notifier->sd = sd;
> +
> + ret = __v4l2_async_notifier_register(notifier);
> + if (ret)
> + notifier->sd = NULL;
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(v4l2_async_subdev_notifier_register);
> +
> void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
> {
> - if (!notifier->v4l2_dev)
> + if (!notifier->v4l2_dev && !notifier->sd)
> return;
>
> mutex_lock(&list_lock);
>
> - list_del(¬ifier->list);
> -
> v4l2_async_notifier_unbind_all_subdevs(notifier);
>
> - mutex_unlock(&list_lock);
> -
> + notifier->sd = NULL;
> notifier->v4l2_dev = NULL;
> +
> + list_del(¬ifier->list);
> +
> + mutex_unlock(&list_lock);
> }
> EXPORT_SYMBOL(v4l2_async_notifier_unregister);
>
> @@ -331,6 +452,7 @@ EXPORT_SYMBOL_GPL(v4l2_async_notifier_cleanup);
>
> int v4l2_async_register_subdev(struct v4l2_subdev *sd)
> {
> + struct v4l2_async_notifier *subdev_notifier;
> struct v4l2_async_notifier *notifier;
> int ret;
>
> @@ -347,24 +469,26 @@ 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);
> + 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, notifier->v4l2_dev, sd,
> asd);
> if (ret)
> - goto err_unlock;
> -
> - if (!list_empty(¬ifier->waiting))
> - goto out_unlock;
> + goto err_unbind;
>
> - ret = v4l2_async_notifier_call_complete(notifier);
> + ret = v4l2_async_notifier_try_complete(notifier);
> if (ret)
> - goto err_cleanup;
> + goto err_unbind;
>
> goto out_unlock;
> }
> @@ -377,11 +501,19 @@ int v4l2_async_register_subdev(struct v4l2_subdev *sd)
>
> return 0;
>
> -err_cleanup:
> - v4l2_async_notifier_call_unbind(notifier, sd, sd->asd);
> +err_unbind:
> + /*
> + * Complete failed. Unbind the sub-devices bound through registering
> + * this async sub-device.
> + */
> + subdev_notifier = v4l2_async_find_subdev_notifier(sd);
> + if (subdev_notifier)
> + v4l2_async_notifier_unbind_all_subdevs(subdev_notifier);
> +
> + if (sd->asd)
> + v4l2_async_notifier_call_unbind(notifier, sd, sd->asd);
> v4l2_async_cleanup(sd);
>
> -err_unlock:
> mutex_unlock(&list_lock);
>
> return ret;
> diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> index 68606afb5ef9..17c4ac7c73e8 100644
> --- a/include/media/v4l2-async.h
> +++ b/include/media/v4l2-async.h
> @@ -82,7 +82,8 @@ struct v4l2_async_subdev {
> /**
> * struct v4l2_async_notifier_operations - Asynchronous V4L2 notifier operations
> * @bound: a subdevice driver has successfully probed one of the subdevices
> - * @complete: all subdevices have been probed successfully
> + * @complete: All subdevices have been probed successfully. The complete
> + * callback is only executed for the root notifier.
> * @unbind: a subdevice is leaving
> */
> struct v4l2_async_notifier_operations {
> @@ -102,7 +103,9 @@ 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 +116,8 @@ 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 +133,16 @@ 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
> --
> 2.11.0
>
--
Regards,
Niklas Söderlund
