Re: [PATCH v2 03/22] media: Media Controller register/unregister entity_notify API

From: Mauro Carvalho Chehab
Date: Thu Feb 04 2016 - 04:03:30 EST

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In reply to: Shuah Khan: "[PATCH v2 03/22] media: Media Controller register/unregister entity_notify API"
Next in thread: Mauro Carvalho Chehab: "Re: [PATCH v2 00/22] Sharing media resources across ALSA and au0828 drivers"
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Em Wed, 03 Feb 2016 21:03:35 -0700
Shuah Khan <shuahkh@xxxxxxxxxxxxxxx> escreveu:

> Add new interfaces to register and unregister entity_notify
> hook to media device. These interfaces allow drivers to add
> hooks to take appropriate actions when new entities get added
> to a shared media device. For example, au0828 bridge driver
> registers an entity_notify hook to create links as needed
> between media graph nodes.

Shuah,

It seems you didn't address the documentation issues I pointed on the
last review. While not ideal, I'll accept, in this specific case,
although this requires an extra time for me (as I want to read the
documentation *before* actually reviewing the patches), I'm OK
if you send the documentation a the end of the series, but please
send it *together* with the patch series.

That affect not only me, but others that build documentation and
gets lots of errors if something is not documented at the right
place.

See below for some notes. I won't be commenting documentation on
the rest of this patch series.

>
> Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
> ---
> drivers/media/media-device.c | 61 ++++++++++++++++++++++++++++++++++++++++++++
> include/media/media-device.h | 25 ++++++++++++++++++
> 2 files changed, 86 insertions(+)
>
> diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
> index 4d1c13d..1f5d67e 100644
> --- a/drivers/media/media-device.c
> +++ b/drivers/media/media-device.c
> @@ -536,6 +536,7 @@ static void media_device_release(struct media_devnode *mdev)
> int __must_check media_device_register_entity(struct media_device *mdev,
> struct media_entity *entity)
> {
> + struct media_entity_notify *notify, *next;
> unsigned int i;
> int ret;
>
> @@ -575,6 +576,11 @@ int __must_check media_device_register_entity(struct media_device *mdev,
> media_gobj_create(mdev, MEDIA_GRAPH_PAD,
> &entity->pads[i].graph_obj);
>
> + /* invoke entity_notify callbacks */
> + list_for_each_entry_safe(notify, next, &mdev->entity_notify, list) {
> + (notify)->notify(entity, notify->notify_data);
> + }
> +
> spin_unlock(&mdev->lock);
>
> return 0;
> @@ -608,6 +614,8 @@ static void __media_device_unregister_entity(struct media_entity *entity)
> /* Remove the entity */
> media_gobj_destroy(&entity->graph_obj);
>
> + /* invoke entity_notify callbacks to handle entity removal?? */
> +
> entity->graph_obj.mdev = NULL;
> }
>
> @@ -640,6 +648,7 @@ void media_device_init(struct media_device *mdev)
> INIT_LIST_HEAD(&mdev->interfaces);
> INIT_LIST_HEAD(&mdev->pads);
> INIT_LIST_HEAD(&mdev->links);
> + INIT_LIST_HEAD(&mdev->entity_notify);
> spin_lock_init(&mdev->lock);
> mutex_init(&mdev->graph_mutex);
> ida_init(&mdev->entity_internal_idx);
> @@ -685,11 +694,59 @@ int __must_check __media_device_register(struct media_device *mdev,
> }
> EXPORT_SYMBOL_GPL(__media_device_register);
>
> +/**
> + * media_device_register_entity_notify - Register a media entity notify
> + * callback with a media device. When a new entity is registered, all
> + * the registered media_entity_notify callbacks are invoked.
> + * @mdev: The media device
> + * @nptr: The media_entity_notify
> + */

Please split the comments into a short description and a detailed
description, and add blank lines to make it easier to be read by
mortals.

The short description appears at the index of the html page:
https://linuxtv.org/downloads/v4l-dvb-internals/device-drivers/ch06s04.html

So, we want it to be short ;)

The detailed description appears at the end:
https://linuxtv.org/downloads/v4l-dvb-internals/device-drivers/API-dvb-create-media-graph.html

Btw, in the above comment, you don't have actually a detailed description,
but, instead, a note. So, the best would be do to it as:

/**
* media_device_register_entity_notify() - Register a media entity notify
* callback with a media device.
*
* @mdev: The media device
* @nptr: The media_entity_notify
*
* NOTE: When a new entity is registered, all the registered
* media_entity_notify callbacks are invoked.
*/

The "NOTE: foo" will appear as:
https://linuxtv.org/downloads/v4l-dvb-internals/device-drivers/API-media-device-register-entity.html

P.S.: Don't forget to test if everything is OK with:
rm Documentation/DocBook/device-drivers.aux.xml Documentation/DocBook/device-drivers.xml
LC_ALL=en_US.UTF-8 make DOCBOOKS=device-drivers.xml htmldocs

The same note applied to the other DocBook tags you added.

Btw, add the documentation *only* at the .h.

> +int __must_check media_device_register_entity_notify(struct media_device *mdev,
> + struct media_entity_notify *nptr)
> +{
> + spin_lock(&mdev->lock);
> + list_add_tail(&nptr->list, &mdev->entity_notify);
> + spin_unlock(&mdev->lock);
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(media_device_register_entity_notify);
> +
> +/**
> + * __media_device_unregister_entity_notify - Unregister a media entity notify
> + * callback with a media device. When a new entity is registered, all
> + * the registered media_entity_notify callbacks are invoked.
> + * @mdev: The media device
> + * @nptr: The media_entity_notify
> + * Non-locking version. Should be called with mdev->lock held.
> + */
> +static void __media_device_unregister_entity_notify(struct media_device *mdev,
> + struct media_entity_notify *nptr)
> +{
> + list_del(&nptr->list);
> +}
> +
> +/**
> + * media_device_unregister_entity_notify - Unregister a media entity notify
> + * callback with a media device. When a new entity is registered, all
> + * the registered media_entity_notify callbacks are invoked.
> + * @mdev: The media device
> + * @nptr: The media_entity_notify
> + */
> +void media_device_unregister_entity_notify(struct media_device *mdev,
> + struct media_entity_notify *nptr)
> +{
> + spin_lock(&mdev->lock);
> + __media_device_unregister_entity_notify(mdev, nptr);
> + spin_unlock(&mdev->lock);
> +}
> +EXPORT_SYMBOL_GPL(media_device_unregister_entity_notify);
> +
> void media_device_unregister(struct media_device *mdev)
> {
> struct media_entity *entity;
> struct media_entity *next;
> struct media_interface *intf, *tmp_intf;
> + struct media_entity_notify *notify, *nextp;
>
> if (mdev == NULL)
> return;
> @@ -706,6 +763,10 @@ void media_device_unregister(struct media_device *mdev)
> list_for_each_entry_safe(entity, next, &mdev->entities, graph_obj.list)
> __media_device_unregister_entity(entity);
>
> + /* Remove all entity_notify callbacks from the media device */
> + list_for_each_entry_safe(notify, nextp, &mdev->entity_notify, list)
> + __media_device_unregister_entity_notify(mdev, notify);
> +
> /* Remove all interfaces from the media device */
> list_for_each_entry_safe(intf, tmp_intf, &mdev->interfaces,
> graph_obj.list) {
> diff --git a/include/media/media-device.h b/include/media/media-device.h
> index d385589..bad8242a 100644
> --- a/include/media/media-device.h
> +++ b/include/media/media-device.h
> @@ -264,6 +264,12 @@
> struct ida;
> struct device;
>
> +struct media_entity_notify {
> + struct list_head list;
> + void *notify_data;
> + void (*notify)(struct media_entity *entity, void *notify_data);
> +};
> +

Documentation is missing.

> /**
> * struct media_device - Media device
> * @dev: Parent device
> @@ -319,6 +325,9 @@ struct media_device {
> struct list_head pads;
> struct list_head links;
>
> + /* notify callback list invoked when a new entity is registered */
> + struct list_head entity_notify;
> +

Documentation is missing. You should have noticed if you tried to
generate the docbook, as it would produce an error like:

include/media/media-device.h:357: warning: No description found for parameter 'entity_notify'

as reported by kbuild test robot.

> /* Protects the graph objects creation/removal */
> spinlock_t lock;
> /* Serializes graph operations. */
> @@ -497,6 +506,11 @@ int __must_check media_device_register_entity(struct media_device *mdev,
> */
> void media_device_unregister_entity(struct media_entity *entity);
>
> +int __must_check media_device_register_entity_notify(struct media_device *mdev,
> + struct media_entity_notify *nptr);
> +void media_device_unregister_entity_notify(struct media_device *mdev,
> + struct media_entity_notify *nptr);
> +

Documentation is missing.

> /**
> * media_device_get_devres() - get media device as device resource
> * creates if one doesn't exist
> @@ -552,6 +566,17 @@ static inline int media_device_register_entity(struct media_device *mdev,
> static inline void media_device_unregister_entity(struct media_entity *entity)
> {
> }
> +static inline int media_device_register_entity_notify(
> + struct media_device *mdev,
> + struct media_entity_notify *nptr)
> +{
> + return 0;
> +}
> +static inline void media_device_unregister_entity_notify(
> + struct media_device *mdev,
> + struct media_entity_notify *nptr)
> +{
> +}

Documentation is missing.

> static inline struct media_device *media_device_get_devres(struct device *dev)
> {
> return NULL;

Next message: Thomas Gleixner: "Re: [PATCH v5] futex: Remove requirement for lock_page in get_futex_key"
Previous message: Ilya Dryomov: "Re: [PATCH 09/10] fs: ceph: Replace CURRENT_TIME by ktime_get_real_ts()"
In reply to: Shuah Khan: "[PATCH v2 03/22] media: Media Controller register/unregister entity_notify API"
Next in thread: Mauro Carvalho Chehab: "Re: [PATCH v2 00/22] Sharing media resources across ALSA and au0828 drivers"
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