Hi Hans,
On Wed, Sep 06, 2017 at 10:46:31AM +0200, Hans Verkuil wrote:
> On 09/05/2017 03:05 PM, 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 to the
>
> to -> in
Fixed.
>
> > 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 master notifier's complete callback is only called when all sub-device
> > notifiers are completed.
> >
> > Signed-off-by: Sakari Ailus <sakari.ai...@linux.intel.com>
> > ---
> > drivers/media/v4l2-core/v4l2-async.c | 209
> > ++++++++++++++++++++++++++++++-----
> > include/media/v4l2-async.h | 16 ++-
> > 2 files changed, 194 insertions(+), 31 deletions(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-async.c
> > b/drivers/media/v4l2-core/v4l2-async.c
> > index 79f216723a3f..620b2cd29fc3 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)
> > @@ -129,14 +133,119 @@ 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(
> > + 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);
> > +
> > + 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->master)
> > + notifier = notifier->master;
> > +
> > + 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, *tmp;
> > +
> > + if (!v4l2_async_notifier_get_v4l2_dev(notifier))
> > + return 0;
> > +
> > + list_for_each_entry_safe(sd, tmp, &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;
> > + }
> > +
> > + 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 master. If there is one, repeat
> > + * the process, otherwise we're done here.
> > + */
> > + } while ((notifier = notifier->master));
>
> I'd change this to:
>
> notifier = notifier->master;
> } while (notifier);
I prefer the original for the same reason as in related case: the loop
condition as well as obtaining the next entry is better separated from
where the real work on the entries takes place.
>
> > +
> > + 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);
> > @@ -153,10 +262,20 @@ 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->master) {
> > + subdev_notifier->master = notifier;
> > + ret = v4l2_async_notifier_try_all_subdevs(subdev_notifier);
> > + if (ret)
> > + return ret;
> > + }
> >
> > - return 0;
> > + /* Try completing the notifier and its master(s). */
> > + return v4l2_async_notifier_try_complete(notifier);
> > }
> >
> > static void v4l2_async_cleanup(struct v4l2_subdev *sd)
> > @@ -168,18 +287,17 @@ 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 ||
> > + if (!notifier->v4l2_dev == !notifier->sd || !notifier->num_subdevs ||
>
> With the changes suggested below this can be changed to:
>
> if (!notifier->num_subdevs ||
>
> However, I have a question about that: why would it be wrong to call this with
> no subdevs in the list?
>
> It's perfectly valid to have no subdevs at all. There may be a fixed incoming
> video
> stream that is not controlled by a subdev. We have a case like that in fact.
I added a separate patch for that earlier in the set.
>
> > notifier->num_subdevs > V4L2_MAX_SUBDEVS)
> > return -EINVAL;
> >
> > - notifier->v4l2_dev = v4l2_dev;
> > + INIT_LIST_HEAD(¬ifier->list);
> > INIT_LIST_HEAD(¬ifier->waiting);
> > INIT_LIST_HEAD(¬ifier->done);
> >
> > @@ -203,18 +321,10 @@ 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 */
> > @@ -224,28 +334,67 @@ 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)
>
> I'd change this to:
>
> if (!v4l2_dev || notifier->sd)
Done.
>
> > + 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)
>
> and this to:
>
> if (!sd || notifier->v4l2_dev)
Done as well. And removed the interesting-looking check from
__v4l2_async_subdev_notifier_register(). :-)
>
> > + 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->master = NULL;
> > +}
> > +
> > +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..12739be44bd1 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 master, for subdev notifiers NULL
> > + * @sd: sub-device that registered the notifier, NULL otherwise
> > + * @master: master notifier carrying @v4l2_dev
>
> I think this description is out of date. It is really the parent notifier,
> right? Should 'master' be renamed to 'parent'?
You could view it as one, yes. What is known is that the notifier is
related, and through which the v4l2_dev can be found. I'll rename it as
"parent".
I'll use root in the commit message as well.
>
> Same problem with the description of @v4l2_dev: it's the v4l2_device of the
> root/top-level notifier.
"v4l2_device of the root notifier, NULL otherwise"?
>
> > * @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 *master;
> > 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
> >
>
> This v8 is much better and is getting close.
Thanks!
--
Regards,
Sakari Ailus
e-mail: sakari.ai...@iki.fi
