Hi Hans,
Thanks for your feedback.
On 2017-07-18 16:22:43 +0200, Hans Verkuil wrote:
> On 17/07/17 18:59, Niklas Söderlund wrote:
> > Add a subdevice specific notifier which can be used by a subdevice
> > driver to compliment the master device notifier to extend the subdevice
>
> compliment -> complement
>
> Just one character difference, but a wildly different meaning :-)
>
> Although it was very polite of the subdevice driver to compliment the
> master driver. Impeccable manners. :-)
It's all about good manners, is it not? But yes the next version of the
series won't be this polite.
>
> > discovery.
> >
> > The master device registers the subdevices closest to itself in its
> > notifier while the subdevice(s) register notifiers for their closest
> > neighboring devices. Subdevice drivers configures a notifier at probe
>
> configures -> configure
>
> > time which are registered by the v4l2-async framework once the subdevice
>
> are -> is
>
> > itself is register, since it's only at this point the v4l2_dev is
>
> register -> registered
Thanks.
>
> > available to the subnotifier.
> >
> > Using this incremental approach two problems can be solved:
> >
> > 1. The master device no longer has to care how many devices exist in
> > the pipeline. It only needs to care about its closest subdevice and
> > arbitrary long pipelines can be created without having to adapt the
> > master device for each case.
> >
> > 2. Subdevices which are represented as a single DT node but register
> > more than one subdevice can use this to improve the pipeline
> > discovery, since the subdevice driver is the only one who knows which
> > of its subdevices is linked with which subdevice of a neighboring DT
> > node.
> >
> > To allow subdevices to provide its own list of subdevices to the
>
> its -> their
Will fix.
>
> > v4l2-async framework v4l2_async_subdev_register_notifier() is added.
> > This new function must be called before the subdevice itself is
> > registered with the v4l2-async framework using
> > v4l2_async_register_subdev().
> >
> > Signed-off-by: Niklas Söderlund <niklas.soderlund+rene...@ragnatech.se>
> > ---
> > Documentation/media/kapi/v4l2-subdev.rst | 12 +++
> > drivers/media/v4l2-core/v4l2-async.c | 134
> > +++++++++++++++++++++++++++++--
> > include/media/v4l2-async.h | 25 ++++++
> > include/media/v4l2-subdev.h | 5 ++
> > 4 files changed, 168 insertions(+), 8 deletions(-)
> >
> > diff --git a/Documentation/media/kapi/v4l2-subdev.rst
> > b/Documentation/media/kapi/v4l2-subdev.rst
> > index e1f0b726e438f963..5957176965a6a3ef 100644
> > --- a/Documentation/media/kapi/v4l2-subdev.rst
> > +++ b/Documentation/media/kapi/v4l2-subdev.rst
> > @@ -262,6 +262,18 @@ is called. After all subdevices have been located the
> > .complete() callback is
> > called. When a subdevice is removed from the system the .unbind() method is
> > called. All three callbacks are optional.
> >
> > +Subdevice drivers might in turn register subnotifier objects with an
> > +array of other subdevice descriptors that the subdevice needs for its
> > +own operation. Subnotifiers are an extension of the bridge drivers
> > +notifier to allow for a incremental registering and matching of
> > +subdevices. This is useful when a driver only has information about
> > +which subdevice is closest to itself and would require knowledge from the
> > +driver of that subdevice to know which other subdevice(s) lie beyond.
> > +By registering subnotifiers drivers can incrementally move the subdevice
> > +matching down the chain of drivers. This is performed using the
> > +:c:func:`v4l2_async_subdev_register_notifier` call which must be performed
> > +before registering the subdevice using
> > :c:func:`v4l2_async_register_subdev`.
> > +
> > V4L2 sub-device userspace API
> > -----------------------------
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-async.c
> > b/drivers/media/v4l2-core/v4l2-async.c
> > index 8fc84f7962386ddd..558fb3ec07e7fba8 100644
> > --- a/drivers/media/v4l2-core/v4l2-async.c
> > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > @@ -100,6 +100,61 @@ static struct v4l2_async_subdev
> > *v4l2_async_belongs(struct v4l2_async_notifier *
> > return NULL;
> > }
> >
> > +static int v4l2_async_notifier_complete(struct v4l2_async_notifier
> > *notifier)
> > +{
> > + struct v4l2_subdev *sd, *tmp;
> > +
> > + if (!notifier->num_subdevs)
> > + return 0;
> > +
> > + list_for_each_entry_safe(sd, tmp, ¬ifier->done, async_list) {
> > + v4l2_async_notifier_complete(&sd->subnotifier);
> > + }
>
> Curly brackets aren't needed here (didn't checkpatch complain about this?)
It did not, and I was unsure how to handle this since
list_for_each_entry_safe() is a macro. Will drop them for next version
provided checkpatch don't complain about it.
>
> > +
> > + if (notifier->complete)
> > + return notifier->complete(notifier);
> > +
> > + return 0;
> > +}
> > +
> > +static bool
> > +v4l2_async_is_notifier_complete(struct v4l2_async_notifier *notifier)
> > +{
> > + struct v4l2_subdev *sd, *tmp;
> > +
> > + if (!list_empty(¬ifier->waiting))
> > + return false;
> > +
> > + list_for_each_entry_safe(sd, tmp, ¬ifier->done, async_list) {
> > + /* Don't consider empty subnotifiers */
> > + if (!sd->subnotifier.num_subdevs)
> > + continue;
> > +
> > + if (!v4l2_async_is_notifier_complete(&sd->subnotifier))
> > + return false;
> > + }
> > +
> > + return true;
> > +}
> > +
> > +static int
> > +v4l2_async_try_complete_notifier(struct v4l2_async_notifier *notifier)
> > +{
> > + struct v4l2_async_notifier *root = notifier;
> > +
> > + while (root->subnotifier) {
> > + root = subnotifier_to_v4l2_subdev(root)->notifier;
> > + /* No root notifier can be found at this time */
> > + if (!root)
> > + return 0;
> > + }
> > +
> > + if (v4l2_async_is_notifier_complete(root))
> > + return v4l2_async_notifier_complete(root);
> > +
> > + return 0;
> > +}
> > +
> > static int v4l2_async_test_notify(struct v4l2_async_notifier *notifier,
> > struct v4l2_subdev *sd,
> > struct v4l2_async_subdev *asd)
> > @@ -119,6 +174,17 @@ static int v4l2_async_test_notify(struct
> > v4l2_async_notifier *notifier,
> > return ret;
> > }
> >
> > + /* Register the subnotifier if it's not empty */
> > + if (sd->subnotifier.num_subdevs) {
> > + ret = v4l2_async_notifier_register(sd->v4l2_dev,
> > + &sd->subnotifier);
> > + if (ret) {
> > + if (notifier->unbind)
> > + notifier->unbind(notifier, sd, asd);
> > + v4l2_device_unregister_subdev(sd);
> > + return ret;
> > + }
> > + }
> > /* Remove from the waiting list */
> > list_del(&asd->list);
> > sd->asd = asd;
> > @@ -127,10 +193,7 @@ static int v4l2_async_test_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) && notifier->complete)
> > - return notifier->complete(notifier);
> > -
> > - return 0;
> > + return v4l2_async_try_complete_notifier(notifier);
> > }
> >
> > static void v4l2_async_cleanup(struct v4l2_subdev *sd)
> > @@ -140,6 +203,7 @@ static void v4l2_async_cleanup(struct v4l2_subdev *sd)
> > list_del_init(&sd->async_list);
> > sd->asd = NULL;
> > sd->dev = NULL;
> > + sd->notifier = NULL;
> > }
> >
> > int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> > @@ -175,8 +239,17 @@ int v4l2_async_notifier_register(struct v4l2_device
> > *v4l2_dev,
> > list_add_tail(&asd->list, ¬ifier->waiting);
> > }
> >
> > - mutex_lock(&list_lock);
> > + if (notifier->subnotifier)
> > + lockdep_assert_held(&list_lock);
> > + else
> > + mutex_lock(&list_lock);
> >
> > + /*
> > + * This function can be called recursively so the list
> > + * might be modified in a recursive call. Start from the
> > + * top of the list each iteration.
> > + */
> > +again:
> > list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
> > int ret;
> >
> > @@ -186,15 +259,18 @@ int v4l2_async_notifier_register(struct v4l2_device
> > *v4l2_dev,
> >
> > ret = v4l2_async_test_notify(notifier, sd, asd);
> > if (ret < 0) {
> > - mutex_unlock(&list_lock);
> > + if (!notifier->subnotifier)
> > + mutex_unlock(&list_lock);
> > return ret;
> > }
> > + goto again;
> > }
> >
> > /* Keep also completed notifiers on the list */
> > list_add(¬ifier->list, ¬ifier_list);
> >
> > - mutex_unlock(&list_lock);
> > + if (!notifier->subnotifier)
> > + mutex_unlock(&list_lock);
> >
> > return 0;
> > }
> > @@ -202,7 +278,7 @@ EXPORT_SYMBOL(v4l2_async_notifier_register);
> >
> > void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
> > {
> > - struct v4l2_subdev *sd, *tmp;
> > + struct v4l2_subdev *sd, *tmp, **subdev;
> > unsigned int notif_n_subdev = notifier->num_subdevs;
> > unsigned int n_subdev = min(notif_n_subdev, V4L2_MAX_SUBDEVS);
> > struct device **dev;
> > @@ -217,6 +293,12 @@ void v4l2_async_notifier_unregister(struct
> > v4l2_async_notifier *notifier)
> > "Failed to allocate device cache!\n");
> > }
> >
> > + subdev = kvmalloc_array(n_subdev, sizeof(*subdev), GFP_KERNEL);
> > + if (!dev) {
> > + dev_err(notifier->v4l2_dev->dev,
> > + "Failed to allocate subdevice cache!\n");
> > + }
> > +
>
> How about making a little struct:
>
> struct whatever {
> struct device *dev;
> struct v4l2_subdev *sd;
> };
>
> and allocate an array of that. Only need to call kvmalloc_array once.
Neat idea, will do so for next version.
>
> Some comments after the dev_err of why you ignore the failed memory allocation
> and what the consequences of that are would be helpful. It is unexpected code,
> and that needs documentation.
I agree that it's unexpected and I don't know the reason for it, I was
just mimic the existing behavior. If you are OK with it I be more then
happy to add patch to this series returning -ENOMEM if the allocation
failed as Geert pointed out if this allocation fails I think we are in a
lot of trouble anyhow...
Let me know what you think, but I don't think I can add a comment
explaining why the function don't simply abort on failure since I don't
understand it myself.
>
> See also my comment for patch 2/3.
>
> > mutex_lock(&list_lock);
> >
> > list_del(¬ifier->list);
> > @@ -224,6 +306,8 @@ void v4l2_async_notifier_unregister(struct
> > v4l2_async_notifier *notifier)
> > list_for_each_entry_safe(sd, tmp, ¬ifier->done, async_list) {
> > if (dev)
> > dev[count] = get_device(sd->dev);
> > + if (subdev)
> > + subdev[count] = sd;
> > count++;
> >
> > if (notifier->unbind)
> > @@ -235,10 +319,15 @@ void v4l2_async_notifier_unregister(struct
> > v4l2_async_notifier *notifier)
> > mutex_unlock(&list_lock);
> >
> > for (i = 0; i < count; i++) {
> > + /* If the subdev have a notifier unregister it */
> > + if (subdev && subdev[i]->subnotifier.num_subdevs)
> > + v4l2_async_notifier_unregister(&subdev[i]->subnotifier);
> > +
> > /* If we handled USB devices, we'd have to lock the parent too
> > */
> > if (dev)
> > device_release_driver(dev[i]);
> > }
> > + kvfree(subdev);
> >
> > /*
> > * Call device_attach() to reprobe devices
> > @@ -313,6 +402,9 @@ void v4l2_async_unregister_subdev(struct v4l2_subdev
> > *sd)
> > return;
> > }
> >
> > + if (sd->subnotifier.num_subdevs)
> > + v4l2_async_notifier_unregister(&sd->subnotifier);
> > +
> > mutex_lock(&list_lock);
> >
> > list_add(&sd->asd->list, ¬ifier->waiting);
> > @@ -325,3 +417,29 @@ void v4l2_async_unregister_subdev(struct v4l2_subdev
> > *sd)
> > mutex_unlock(&list_lock);
> > }
> > EXPORT_SYMBOL(v4l2_async_unregister_subdev);
> > +
> > +int v4l2_async_subdev_register_notifier(
>
> Since it is v4l2_async_notifier_register(), shouldn't this be
> v4l2_async_subdev_notifier_register()?
Yes that makes more since.
>
> > + struct v4l2_subdev *sd,
> > + unsigned int num_subdevs,
> > + struct v4l2_async_subdev **subdevs,
> > + int (*bound)(struct v4l2_async_notifier *notifier,
> > + struct v4l2_subdev *subdev,
> > + struct v4l2_async_subdev *asd),
> > + int (*complete)(struct v4l2_async_notifier *notifier),
> > + void (*unbind)(struct v4l2_async_notifier *notifier,
> > + struct v4l2_subdev *subdev,
> > + struct v4l2_async_subdev *asd))
> > +{
> > + if (!sd)
>
> Test for '!num_subdevs || !subdevs' as well?
Good point, will do so.
>
> > + return -EINVAL;
> > +
> > + sd->subnotifier.subnotifier = true;
> > + sd->subnotifier.num_subdevs = num_subdevs;
> > + sd->subnotifier.subdevs = subdevs;
> > + sd->subnotifier.bound = bound;
> > + sd->subnotifier.complete = complete;
> > + sd->subnotifier.unbind = unbind;
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL(v4l2_async_subdev_register_notifier);
> > diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> > index c69d8c8a66d0093a..4f142a22373450af 100644
> > --- a/include/media/v4l2-async.h
> > +++ b/include/media/v4l2-async.h
> > @@ -78,6 +78,7 @@ struct v4l2_async_subdev {
> > /**
> > * struct v4l2_async_notifier - v4l2_device notifier data
> > *
> > + * @subnotifier: flag if this notifier is part of a v4l2_subdev
> > * @num_subdevs: number of subdevices
> > * @subdevs: array of pointers to subdevice descriptors
> > * @v4l2_dev: pointer to struct v4l2_device
> > @@ -89,6 +90,7 @@ struct v4l2_async_subdev {
> > * @unbind: a subdevice is leaving
> > */
> > struct v4l2_async_notifier {
> > + bool subnotifier;
> > unsigned int num_subdevs;
> > struct v4l2_async_subdev **subdevs;
> > struct v4l2_device *v4l2_dev;
> > @@ -135,4 +137,27 @@ int v4l2_async_register_subdev(struct v4l2_subdev *sd);
> > * @sd: pointer to &struct v4l2_subdev
> > */
> > void v4l2_async_unregister_subdev(struct v4l2_subdev *sd);
> > +
> > +/**
> > + * v4l2_async_subdev_register_notifier - registers a subdevice asynchronous
> > + * subnotifier
> > + *
> > + * @sd: pointer to &struct v4l2_subdev
> > + * @num_subdevs: number of subdevices
> > + * @subdevs: array of pointers to subdevice descriptors
> > + * @bound: a subdevice driver has successfully probed one of subdevices
> > + * @complete: all subdevices have been probed successfully
> > + * @unbind: a subdevice is leaving
> > + */
> > +int v4l2_async_subdev_register_notifier(
> > + struct v4l2_subdev *sd,
> > + unsigned int num_subdevs,
> > + struct v4l2_async_subdev **subdevs,
> > + int (*bound)(struct v4l2_async_notifier *notifier,
> > + struct v4l2_subdev *subdev,
> > + struct v4l2_async_subdev *asd),
> > + int (*complete)(struct v4l2_async_notifier *notifier),
> > + void (*unbind)(struct v4l2_async_notifier *notifier,
> > + struct v4l2_subdev *subdev,
> > + struct v4l2_async_subdev *asd));
> > #endif
> > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> > index 0f92ebd2d7101acf..13a04af16a627394 100644
> > --- a/include/media/v4l2-subdev.h
> > +++ b/include/media/v4l2-subdev.h
> > @@ -793,6 +793,7 @@ struct v4l2_subdev_platform_data {
> > * list.
> > * @asd: Pointer to respective &struct v4l2_async_subdev.
> > * @notifier: Pointer to the managing notifier.
> > + * @subnotifier: Notifier for devices the subdevice depends on
> > * @pdata: common part of subdevice platform data
> > *
> > * Each instance of a subdev driver should create this struct, either
> > @@ -823,6 +824,7 @@ struct v4l2_subdev {
> > struct list_head async_list;
> > struct v4l2_async_subdev *asd;
> > struct v4l2_async_notifier *notifier;
> > + struct v4l2_async_notifier subnotifier;
> > struct v4l2_subdev_platform_data *pdata;
> > };
> >
> > @@ -838,6 +840,9 @@ struct v4l2_subdev {
> > #define vdev_to_v4l2_subdev(vdev) \
> > ((struct v4l2_subdev *)video_get_drvdata(vdev))
> >
> > +#define subnotifier_to_v4l2_subdev(sub) \
> > + container_of(sub, struct v4l2_subdev, subnotifier)
> > +
> > /**
> > * struct v4l2_subdev_fh - Used for storing subdev information per file
> > handle
> > *
> >
>
> Regards,
>
> Hans
--
Regards,
Niklas Söderlund
