Re: [PATCH v10 14/24] v4l: async: Allow binding notifiers to sub-devices
Hi Hans,
Thanks for the review!
On Mon, Sep 11, 2017 at 10:57:16AM +0200, Hans Verkuil wrote:
> 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
> > ---
> > 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...".
Yes, makes sense. Get also suggests that there would be reference counting
which is not the case here.
I made the corresponding change to v4l2_async_notifier_find_v4l2_dev() as
well.
>
> > + 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.
I thought of that, but ended up keeping the information in the notifier. As
the information is already available elsewhere, I didn't end up adding a
new field for the purpose. This is certainly not performance critical
either.
>
> > +
> > + 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(no
Re: [PATCH v10 14/24] v4l: async: Allow binding notifiers to sub-devices
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
> ---
> 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_noti
[PATCH v10 14/24] v4l: async: Allow binding notifiers to sub-devices
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
---
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(
+ 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->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
+* t
