On 09/11/2017 09:59 AM, 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.ailus@xxxxxxxxxxxxxxx>
> ---
> drivers/media/v4l2-core/v4l2-async.c | 217 ++++++++++++++++++++++++++++++-----
> include/media/v4l2-async.h | 16 ++-
> 2 files changed, 202 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> index 9ebc2e079d03..6f788b2e922a 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -53,6 +53,10 @@ static int v4l2_async_notifier_call_complete(struct v4l2_async_notifier *n)
> return n->ops->complete(n);
> }
>
> +static int v4l2_async_match_notify(struct v4l2_async_notifier *notifier,
> + struct v4l2_subdev *sd,
> + struct v4l2_async_subdev *asd);
> +
> static bool match_i2c(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
> {
> #if IS_ENABLED(CONFIG_I2C)
> @@ -124,14 +128,128 @@ static struct v4l2_async_subdev *v4l2_async_find_match(
> return NULL;
> }
>
> +/* Get the sub-device notifier registered by a sub-device driver. */
> +static struct v4l2_async_notifier *v4l2_async_get_subdev_notifier(
I prefer to call this v4l2_async_find_subdev_notifier(). 'get' suggests
a getter function, but this actually has to find it. I think this may have
confused me during an earlier review of this code. The comment also needs
updating: "Find the sub-device...".
> + 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;
> +}
> +
> +/* Return true if all sub-device notifiers are complete, false otherwise. */
> +static bool v4l2_async_subdev_notifiers_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_get_subdev_notifier(sd);
Would it make sense to add a 'struct v4l2_async_notifier *subdev_notifier'
field to struct v4l2_subdev? It's set when a subdev registers a notifier.
That way you can just use sd->subdev_notifier here.
I wonder if v4l2_async_get_subdev_notifier() is needed at all if you do
this.
> +
> + if (!subdev_notifier)
> + continue;
> +
> + if (!v4l2_async_subdev_notifiers_complete(subdev_notifier))
> + return false;
> + }
> +
> + return true;
> +}
> +
> +/* Get v4l2_device related to the notifier if one can be found. */
> +static struct v4l2_device *v4l2_async_notifier_get_v4l2_dev(
> + struct v4l2_async_notifier *notifier)
> +{
> + while (notifier->parent)
> + notifier = notifier->parent;
> +
> + return notifier->v4l2_dev;
> +}
> +
> +/* 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_subdev *sd;
> +
> + if (!v4l2_async_notifier_get_v4l2_dev(notifier))
> + return 0;
> +
> +again:
> + list_for_each_entry(sd, &subdev_list, async_list) {
> + struct v4l2_async_subdev *asd;
> + int ret;
> +
> + asd = v4l2_async_find_match(notifier, sd);
> + if (!asd)
> + continue;
> +
> + ret = v4l2_async_match_notify(notifier, 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;
> +}
> +
> +/* Try completing a notifier. */
> +static int v4l2_async_notifier_try_complete(
> + struct v4l2_async_notifier *notifier)
> +{
> + do {
> + int ret;
> +
> + /* Any local async sub-devices left? */
> + if (!list_empty(¬ifier->waiting))
> + return 0;
> +
> + /*
> + * Any sub-device notifiers waiting for async subdevs
> + * to be bound?
> + */
> + if (!v4l2_async_subdev_notifiers_complete(notifier))
> + return 0;
> +
> + /* Proceed completing the notifier */
> + ret = v4l2_async_notifier_call_complete(notifier);
> + if (ret < 0)
> + return ret;
> +
> + /*
> + * Obtain notifier's parent. If there is one, repeat
> + * the process, otherwise we're done here.
> + */
> + } while ((notifier = notifier->parent));
> +
> + return 0;
> +}
> +
> static int v4l2_async_match_notify(struct v4l2_async_notifier *notifier,
> struct v4l2_subdev *sd,
> struct v4l2_async_subdev *asd)
> {
> + struct v4l2_async_notifier *subdev_notifier;
> int ret;
>
> - ret = v4l2_device_register_subdev(notifier->v4l2_dev, sd);
> - if (ret < 0)
> + ret = v4l2_device_register_subdev(
> + v4l2_async_notifier_get_v4l2_dev(notifier), sd);
> + if (ret)
> return ret;
>
> ret = v4l2_async_notifier_call_bound(notifier, sd, asd);
> @@ -148,10 +266,20 @@ 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_get_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;
> + /* Try completing the notifier and its parent(s). */
> + return v4l2_async_notifier_try_complete(notifier);
> }
>
> static void v4l2_async_cleanup(struct v4l2_subdev *sd)
> @@ -163,20 +291,18 @@ static void v4l2_async_cleanup(struct v4l2_subdev *sd)
> sd->dev = NULL;
> }
>
> -int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> - struct v4l2_async_notifier *notifier)
> +static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> {
> - struct v4l2_subdev *sd, *tmp;
> struct v4l2_async_subdev *asd;
> + int ret;
> int i;
>
> - if (!v4l2_dev || notifier->num_subdevs > V4L2_MAX_SUBDEVS)
> + if (notifier->num_subdevs > V4L2_MAX_SUBDEVS)
> return -EINVAL;
>
> if (!notifier->num_subdevs)
> return v4l2_async_notifier_call_complete(notifier);
>
> - notifier->v4l2_dev = v4l2_dev;
> INIT_LIST_HEAD(¬ifier->waiting);
> INIT_LIST_HEAD(¬ifier->done);
>
> @@ -200,18 +326,10 @@ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
>
> mutex_lock(&list_lock);
>
> - list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
> - int ret;
> -
> - asd = v4l2_async_find_match(notifier, sd);
> - if (!asd)
> - continue;
> -
> - ret = v4l2_async_match_notify(notifier, sd, asd);
> - if (ret < 0) {
> - mutex_unlock(&list_lock);
> - return ret;
> - }
> + ret = v4l2_async_notifier_try_all_subdevs(notifier);
> + if (ret) {
> + mutex_unlock(&list_lock);
> + return ret;
> }
>
> /* Keep also completed notifiers on the list */
> @@ -221,28 +339,67 @@ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
>
> return 0;
> }
> +
> +int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> + struct v4l2_async_notifier *notifier)
> +{
> + if (!v4l2_dev || notifier->sd)
Should this be a WARN_ON?
> + return -EINVAL;
> +
> + notifier->v4l2_dev = v4l2_dev;
> +
> + return __v4l2_async_notifier_register(notifier);
> +}
> 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 (!sd || notifier->v4l2_dev)
Ditto.
> + 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_get_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);
> +
> + list_del(&sd->async_list);
> + list_add(&sd->async_list, &subdev_list);
> }
>
> - mutex_unlock(&list_lock);
> + notifier->parent = NULL;
Shouldn't notifier->v4l2_dev and notifier->sd be set to NULL as well?
I can't really tell.
> +}
> +
> +void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
> +{
> + if (!notifier->v4l2_dev && !notifier->sd)
> + return;
>
> - notifier->v4l2_dev = NULL;
> + mutex_lock(&list_lock);
> +
> + v4l2_async_notifier_unbind_all_subdevs(notifier);
> +
> + list_del(¬ifier->list);
> +
> + mutex_unlock(&list_lock);
> }
> EXPORT_SYMBOL(v4l2_async_notifier_unregister);
>
> diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> index 3bc8a7c0d83f..cf409d45208c 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 carrying @v4l2_dev
That's not correct, it only carries v4l2_dev if it is the root notifier.
I think just 'parent notifier' is sufficient here.
> * @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
>
Regards,
Hans
