subject:"Re\: \[PATCH v2 03\/22\] media\: Add an API to manage entity enumerations"

Re: [PATCH v2 03/22] media: Add an API to manage entity enumerations

2015-12-16 Thread Mauro Carvalho Chehab

Em Wed, 16 Dec 2015 01:16:30 +0200
Sakari Ailus  escreveu:

> Hi Mauro,
> 
> On Sun, Dec 13, 2015 at 10:54:57PM -0200, Mauro Carvalho Chehab wrote:
> > > >> +  e->idx_max = idx_max;
> > > >> +
> > > >> +  return 0;
> > > >> +}
> > > >> +EXPORT_SYMBOL_GPL(__media_entity_enum_init);
> > > >> +
> > > >> +/**
> > > >> + * media_entity_enum_cleanup - Release resources of an entity 
> > > >> enumeration
> > > >> + *
> > > >> + * @e: Entity enumeration to be released
> > > >> + */
> > > >> +void media_entity_enum_cleanup(struct media_entity_enum *e)
> > > >> +{
> > > >> +  if (e->e != e->__e)
> > > >> +  kfree(e->e);
> > > >> +  e->e = NULL;
> > > >> +}
> > > >> +EXPORT_SYMBOL_GPL(media_entity_enum_cleanup);
> > > >> +
> > > >> +/**
> > > >>   * media_entity_init - Initialize a media entity
> > > >>   *
> > > >>   * @num_pads: Total number of sink and source pads.
> > > >> diff --git a/include/media/media-device.h 
> > > >> b/include/media/media-device.h
> > > >> index c0e1764..2d46c66 100644
> > > >> --- a/include/media/media-device.h
> > > >> +++ b/include/media/media-device.h
> > > >> @@ -110,6 +110,20 @@ struct media_device {
> > > >>  /* media_devnode to media_device */
> > > >>  #define to_media_device(node) container_of(node, struct media_device, 
> > > >> devnode)
> > > >>  
> > > >> +/**
> > > >> + * media_entity_enum_init - Initialise an entity enumeration
> > > >> + *
> > > >> + * @e: Entity enumeration to be initialised
> > > >> + * @mdev: The related media device
> > > >> + *
> > > >> + * Returns zero on success or a negative error code.
> > > >> + */
> > > >> +static inline __must_check int media_entity_enum_init(
> > > >> +  struct media_entity_enum *e, struct media_device *mdev)
> > > >> +{
> > > >> +  return __media_entity_enum_init(e, 
> > > >> mdev->entity_internal_idx_max + 1);
> > > >> +}
> > > >> +
> > > >>  void media_device_init(struct media_device *mdev);
> > > >>  void media_device_cleanup(struct media_device *mdev);
> > > >>  int __must_check __media_device_register(struct media_device *mdev,
> > > >> diff --git a/include/media/media-entity.h 
> > > >> b/include/media/media-entity.h
> > > >> index d3d3a39..5a0339a 100644
> > > >> --- a/include/media/media-entity.h
> > > >> +++ b/include/media/media-entity.h
> > > >> @@ -23,7 +23,7 @@
> > > >>  #ifndef _MEDIA_ENTITY_H
> > > >>  #define _MEDIA_ENTITY_H
> > > >>  
> > > >> -#include 
> > > >> +#include 
> > > >>  #include 
> > > >>  #include 
> > > >>  #include 
> > > >> @@ -71,6 +71,30 @@ struct media_gobj {
> > > >>struct list_headlist;
> > > >>  };
> > > >>  
> > > >> +#define MEDIA_ENTITY_ENUM_MAX_DEPTH   16
> > > >> +#define MEDIA_ENTITY_ENUM_MAX_ID  64
> > > >> +
> > > >> +/*
> > > >> + * The number of pads can't be bigger than the number of entities,
> > > >> + * as the worse-case scenario is to have one entity linked up to
> > > >> + * MEDIA_ENTITY_ENUM_MAX_ID - 1 entities.
> > > >> + */
> > > >> +#define MEDIA_ENTITY_MAX_PADS (MEDIA_ENTITY_ENUM_MAX_ID - 1)
> > > >> +
> > > >> +/* struct media_entity_enum - An enumeration of media entities.
> > > >> + *
> > > >> + * @__e:  Pre-allocated space reserved for media entities if the 
> > > >> total
> > > >> + *number of entities  does not exceed 
> > > >> MEDIA_ENTITY_ENUM_MAX_ID.
> > > >> + * @e:Bit mask in which each bit represents one 
> > > >> entity at struct
> > > >> + *media_entity->internal_idx.
> > > >> + * @idx_max:  Number of bits in the enum.
> > > >> + */
> > > >> +struct media_entity_enum {
> > > >> +  DECLARE_BITMAP(__e, MEDIA_ENTITY_ENUM_MAX_ID);
> > > >> +  unsigned long *e;
> > > > 
> > > > As mentioned before, don't use single letter names, specially inside
> > > > publicly used structures. There's no good reason for that, and the
> > > > code become really obscure.
> > > > 
> > > > Also, just declare one bitmap. having a "pre-allocated" hardcoded
> > > > one here is very confusing.
> > > 
> > > I prefer to keep it as allocating a few bytes of memory is silly. In the
> > > vast majority of the cases the pre-allocated array will be sufficient.
> > 
> > "vast majority" actually depends on the driver/subsystem. The fact that
> > right now most drivers work fine with < 64 entities may not be
> > true in the future.
> 
> One reason the pre-allocated bitmap shouldn't be removed yet is that by
> doing that, i.e. allocating memory in media_entity_enum_init(), the user
> must check the return code. The further patches in the set make drivers do
> that add __must_check modifier to the prototype.
> 
> I will thus add another patch near the top to remove the pre-allocated
> bitmap.

Works for me.

Regards,
Mauro
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Re: [PATCH v2 03/22] media: Add an API to manage entity enumerations

2015-12-15 Thread Sakari Ailus

Hi Mauro,

On Sun, Dec 13, 2015 at 10:54:57PM -0200, Mauro Carvalho Chehab wrote:
> > >> +e->idx_max = idx_max;
> > >> +
> > >> +return 0;
> > >> +}
> > >> +EXPORT_SYMBOL_GPL(__media_entity_enum_init);
> > >> +
> > >> +/**
> > >> + * media_entity_enum_cleanup - Release resources of an entity 
> > >> enumeration
> > >> + *
> > >> + * @e: Entity enumeration to be released
> > >> + */
> > >> +void media_entity_enum_cleanup(struct media_entity_enum *e)
> > >> +{
> > >> +if (e->e != e->__e)
> > >> +kfree(e->e);
> > >> +e->e = NULL;
> > >> +}
> > >> +EXPORT_SYMBOL_GPL(media_entity_enum_cleanup);
> > >> +
> > >> +/**
> > >>   * media_entity_init - Initialize a media entity
> > >>   *
> > >>   * @num_pads: Total number of sink and source pads.
> > >> diff --git a/include/media/media-device.h b/include/media/media-device.h
> > >> index c0e1764..2d46c66 100644
> > >> --- a/include/media/media-device.h
> > >> +++ b/include/media/media-device.h
> > >> @@ -110,6 +110,20 @@ struct media_device {
> > >>  /* media_devnode to media_device */
> > >>  #define to_media_device(node) container_of(node, struct media_device, 
> > >> devnode)
> > >>  
> > >> +/**
> > >> + * media_entity_enum_init - Initialise an entity enumeration
> > >> + *
> > >> + * @e: Entity enumeration to be initialised
> > >> + * @mdev: The related media device
> > >> + *
> > >> + * Returns zero on success or a negative error code.
> > >> + */
> > >> +static inline __must_check int media_entity_enum_init(
> > >> +struct media_entity_enum *e, struct media_device *mdev)
> > >> +{
> > >> +return __media_entity_enum_init(e, 
> > >> mdev->entity_internal_idx_max + 1);
> > >> +}
> > >> +
> > >>  void media_device_init(struct media_device *mdev);
> > >>  void media_device_cleanup(struct media_device *mdev);
> > >>  int __must_check __media_device_register(struct media_device *mdev,
> > >> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> > >> index d3d3a39..5a0339a 100644
> > >> --- a/include/media/media-entity.h
> > >> +++ b/include/media/media-entity.h
> > >> @@ -23,7 +23,7 @@
> > >>  #ifndef _MEDIA_ENTITY_H
> > >>  #define _MEDIA_ENTITY_H
> > >>  
> > >> -#include 
> > >> +#include 
> > >>  #include 
> > >>  #include 
> > >>  #include 
> > >> @@ -71,6 +71,30 @@ struct media_gobj {
> > >>  struct list_headlist;
> > >>  };
> > >>  
> > >> +#define MEDIA_ENTITY_ENUM_MAX_DEPTH 16
> > >> +#define MEDIA_ENTITY_ENUM_MAX_ID64
> > >> +
> > >> +/*
> > >> + * The number of pads can't be bigger than the number of entities,
> > >> + * as the worse-case scenario is to have one entity linked up to
> > >> + * MEDIA_ENTITY_ENUM_MAX_ID - 1 entities.
> > >> + */
> > >> +#define MEDIA_ENTITY_MAX_PADS   (MEDIA_ENTITY_ENUM_MAX_ID - 1)
> > >> +
> > >> +/* struct media_entity_enum - An enumeration of media entities.
> > >> + *
> > >> + * @__e:Pre-allocated space reserved for media entities if the 
> > >> total
> > >> + *  number of entities  does not exceed 
> > >> MEDIA_ENTITY_ENUM_MAX_ID.
> > >> + * @e:  Bit mask in which each bit represents one entity at 
> > >> struct
> > >> + *  media_entity->internal_idx.
> > >> + * @idx_max:Number of bits in the enum.
> > >> + */
> > >> +struct media_entity_enum {
> > >> +DECLARE_BITMAP(__e, MEDIA_ENTITY_ENUM_MAX_ID);
> > >> +unsigned long *e;
> > > 
> > > As mentioned before, don't use single letter names, specially inside
> > > publicly used structures. There's no good reason for that, and the
> > > code become really obscure.
> > > 
> > > Also, just declare one bitmap. having a "pre-allocated" hardcoded
> > > one here is very confusing.
> > 
> > I prefer to keep it as allocating a few bytes of memory is silly. In the
> > vast majority of the cases the pre-allocated array will be sufficient.
> 
> "vast majority" actually depends on the driver/subsystem. The fact that
> right now most drivers work fine with < 64 entities may not be
> true in the future.

One reason the pre-allocated bitmap shouldn't be removed yet is that by
doing that, i.e. allocating memory in media_entity_enum_init(), the user
must check the return code. The further patches in the set make drivers do
that add __must_check modifier to the prototype.

I will thus add another patch near the top to remove the pre-allocated
bitmap.

-- 
Kind regards,

Sakari Ailus
e-mail: sakari.ai...@iki.fi XMPP: sai...@retiisi.org.uk
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Re: [PATCH v2 03/22] media: Add an API to manage entity enumerations

2015-12-13 Thread Sakari Ailus

Hi Mauro,

Thanks for the comments!

Mauro Carvalho Chehab wrote:
> Hi Sakari,
> 
> Em Sun, 29 Nov 2015 21:20:04 +0200
> Sakari Ailus  escreveu:
> 
>> From: Sakari Ailus 
>>
>> This is useful in e.g. knowing whether certain operations have already
>> been performed for an entity. The users include the framework itself (for
>> graph walking) and a number of drivers.
> 
> Please use better names on the vars. See below for details.
> 
>>
>> Signed-off-by: Sakari Ailus 
>> ---
>>  drivers/media/media-entity.c |  39 +
>>  include/media/media-device.h |  14 +
>>  include/media/media-entity.h | 136 
>> ---
>>  3 files changed, 181 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
>> index d11f440..fceaf44 100644
>> --- a/drivers/media/media-entity.c
>> +++ b/drivers/media/media-entity.c
>> @@ -213,6 +213,45 @@ void media_gobj_remove(struct media_gobj *gobj)
>>  }
>>  
>>  /**
>> + * __media_entity_enum_init - Initialise an entity enumeration
>> + *
>> + * @e: Entity enumeration to be initialised
>> + * @idx_max: Maximum number of entities in the enumeration
>> + *
>> + * Returns zero on success or a negative error code.
>> + */
> 
> We're using kernel-doc macros only at the header files. Please
> move those macros to there.

Oops. Will fix.

> 
>> +int __media_entity_enum_init(struct media_entity_enum *e, int idx_max)
> 
> using "e" as a var is not nice, specially on a public header.
> 
> I would use "ent_enum" instead for media_entity_enum pointers. This
> applies everywhere on this patch series.

I'm fine with that suggestion, I'll change to use ent_enum instead
(where there's no more specific purpose for the variable / field).

> 
>> +{
>> +if (idx_max > MEDIA_ENTITY_ENUM_MAX_ID) {
>> +e->e = kcalloc(DIV_ROUND_UP(idx_max, BITS_PER_LONG),
>> +   sizeof(long), GFP_KERNEL);
>> +if (!e->e)
>> +return -ENOMEM;
>> +} else {
>> +e->e = e->__e;
> 
> This is crap! I can't tell what the above code is doing,
> as the var names don't give any clue!

In retrospect, the names could perhaps have been more descriptive.
There's no need to be angry at the letter "e" however, it's just doing
its job...

> 
>> +}
>> +
>> +bitmap_zero(e->e, idx_max);
> 
> Ok, here, there's a hint that one of the "e" is a bitmap, while
> the other is a struct... Weird, and very easy to do wrong things!
> 
> Please name the bitmap as "ent_enum_bmap" or something like that.

Fine with that.

> 
>> +e->idx_max = idx_max;
>> +
>> +return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(__media_entity_enum_init);
>> +
>> +/**
>> + * media_entity_enum_cleanup - Release resources of an entity enumeration
>> + *
>> + * @e: Entity enumeration to be released
>> + */
>> +void media_entity_enum_cleanup(struct media_entity_enum *e)
>> +{
>> +if (e->e != e->__e)
>> +kfree(e->e);
>> +e->e = NULL;
>> +}
>> +EXPORT_SYMBOL_GPL(media_entity_enum_cleanup);
>> +
>> +/**
>>   * media_entity_init - Initialize a media entity
>>   *
>>   * @num_pads: Total number of sink and source pads.
>> diff --git a/include/media/media-device.h b/include/media/media-device.h
>> index c0e1764..2d46c66 100644
>> --- a/include/media/media-device.h
>> +++ b/include/media/media-device.h
>> @@ -110,6 +110,20 @@ struct media_device {
>>  /* media_devnode to media_device */
>>  #define to_media_device(node) container_of(node, struct media_device, 
>> devnode)
>>  
>> +/**
>> + * media_entity_enum_init - Initialise an entity enumeration
>> + *
>> + * @e: Entity enumeration to be initialised
>> + * @mdev: The related media device
>> + *
>> + * Returns zero on success or a negative error code.
>> + */
>> +static inline __must_check int media_entity_enum_init(
>> +struct media_entity_enum *e, struct media_device *mdev)
>> +{
>> +return __media_entity_enum_init(e, mdev->entity_internal_idx_max + 1);
>> +}
>> +
>>  void media_device_init(struct media_device *mdev);
>>  void media_device_cleanup(struct media_device *mdev);
>>  int __must_check __media_device_register(struct media_device *mdev,
>> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
>> index d3d3a39..5a0339a 100644
>> --- a/include/media/media-entity.h
>> +++ b/include/media/media-entity.h
>> @@ -23,7 +23,7 @@
>>  #ifndef _MEDIA_ENTITY_H
>>  #define _MEDIA_ENTITY_H
>>  
>> -#include 
>> +#include 
>>  #include 
>>  #include 
>>  #include 
>> @@ -71,6 +71,30 @@ struct media_gobj {
>>  struct list_headlist;
>>  };
>>  
>> +#define MEDIA_ENTITY_ENUM_MAX_DEPTH 16
>> +#define MEDIA_ENTITY_ENUM_MAX_ID64
>> +
>> +/*
>> + * The number of pads can't be bigger than the number of entities,
>> + * as the worse-case scenario is to have one entity linked up to
>> + * MEDIA_ENTITY_ENUM_MAX_ID - 1 entities.
>>

Re: [PATCH v2 03/22] media: Add an API to manage entity enumerations

2015-12-13 Thread Mauro Carvalho Chehab

Em Mon, 14 Dec 2015 00:12:08 +0200
Sakari Ailus  escreveu:

> Hi Mauro,
> 
> Thanks for the comments!
> 
> Mauro Carvalho Chehab wrote:
> > Hi Sakari,
> > 
> > Em Sun, 29 Nov 2015 21:20:04 +0200
> > Sakari Ailus  escreveu:
> > 
> >> From: Sakari Ailus 
> >>
> >> This is useful in e.g. knowing whether certain operations have already
> >> been performed for an entity. The users include the framework itself (for
> >> graph walking) and a number of drivers.
> > 
> > Please use better names on the vars. See below for details.
> > 
> >>
> >> Signed-off-by: Sakari Ailus 
> >> ---
> >>  drivers/media/media-entity.c |  39 +
> >>  include/media/media-device.h |  14 +
> >>  include/media/media-entity.h | 136 
> >> ---
> >>  3 files changed, 181 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
> >> index d11f440..fceaf44 100644
> >> --- a/drivers/media/media-entity.c
> >> +++ b/drivers/media/media-entity.c
> >> @@ -213,6 +213,45 @@ void media_gobj_remove(struct media_gobj *gobj)
> >>  }
> >>  
> >>  /**
> >> + * __media_entity_enum_init - Initialise an entity enumeration
> >> + *
> >> + * @e: Entity enumeration to be initialised
> >> + * @idx_max: Maximum number of entities in the enumeration
> >> + *
> >> + * Returns zero on success or a negative error code.
> >> + */
> > 
> > We're using kernel-doc macros only at the header files. Please
> > move those macros to there.
> 
> Oops. Will fix.
> 
> > 
> >> +int __media_entity_enum_init(struct media_entity_enum *e, int idx_max)
> > 
> > using "e" as a var is not nice, specially on a public header.
> > 
> > I would use "ent_enum" instead for media_entity_enum pointers. This
> > applies everywhere on this patch series.
> 
> I'm fine with that suggestion, I'll change to use ent_enum instead
> (where there's no more specific purpose for the variable / field).

Thanks!
> 
> > 
> >> +{
> >> +  if (idx_max > MEDIA_ENTITY_ENUM_MAX_ID) {
> >> +  e->e = kcalloc(DIV_ROUND_UP(idx_max, BITS_PER_LONG),
> >> + sizeof(long), GFP_KERNEL);
> >> +  if (!e->e)
> >> +  return -ENOMEM;
> >> +  } else {
> >> +  e->e = e->__e;
> > 
> > This is crap! I can't tell what the above code is doing,
> > as the var names don't give any clue!
> 
> In retrospect, the names could perhaps have been more descriptive.
> There's no need to be angry at the letter "e" however, it's just doing
> its job...

I'm not angry with the letter "e" (or with you). Just the above code
seems too obscure for a poor reviewer ;)

> 
> > 
> >> +  }
> >> +
> >> +  bitmap_zero(e->e, idx_max);
> > 
> > Ok, here, there's a hint that one of the "e" is a bitmap, while
> > the other is a struct... Weird, and very easy to do wrong things!
> > 
> > Please name the bitmap as "ent_enum_bmap" or something like that.
> 
> Fine with that.
> 
> > 
> >> +  e->idx_max = idx_max;
> >> +
> >> +  return 0;
> >> +}
> >> +EXPORT_SYMBOL_GPL(__media_entity_enum_init);
> >> +
> >> +/**
> >> + * media_entity_enum_cleanup - Release resources of an entity enumeration
> >> + *
> >> + * @e: Entity enumeration to be released
> >> + */
> >> +void media_entity_enum_cleanup(struct media_entity_enum *e)
> >> +{
> >> +  if (e->e != e->__e)
> >> +  kfree(e->e);
> >> +  e->e = NULL;
> >> +}
> >> +EXPORT_SYMBOL_GPL(media_entity_enum_cleanup);
> >> +
> >> +/**
> >>   * media_entity_init - Initialize a media entity
> >>   *
> >>   * @num_pads: Total number of sink and source pads.
> >> diff --git a/include/media/media-device.h b/include/media/media-device.h
> >> index c0e1764..2d46c66 100644
> >> --- a/include/media/media-device.h
> >> +++ b/include/media/media-device.h
> >> @@ -110,6 +110,20 @@ struct media_device {
> >>  /* media_devnode to media_device */
> >>  #define to_media_device(node) container_of(node, struct media_device, 
> >> devnode)
> >>  
> >> +/**
> >> + * media_entity_enum_init - Initialise an entity enumeration
> >> + *
> >> + * @e: Entity enumeration to be initialised
> >> + * @mdev: The related media device
> >> + *
> >> + * Returns zero on success or a negative error code.
> >> + */
> >> +static inline __must_check int media_entity_enum_init(
> >> +  struct media_entity_enum *e, struct media_device *mdev)
> >> +{
> >> +  return __media_entity_enum_init(e, mdev->entity_internal_idx_max + 1);
> >> +}
> >> +
> >>  void media_device_init(struct media_device *mdev);
> >>  void media_device_cleanup(struct media_device *mdev);
> >>  int __must_check __media_device_register(struct media_device *mdev,
> >> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> >> index d3d3a39..5a0339a 100644
> >> --- a/include/media/media-entity.h
> >> +++ b/include/media/media-entity.h
> >> @@ -23,7 +23,7 @@
> >>  #ifndef _MEDIA_ENTITY_H
> >>  #define

Re: [PATCH v2 03/22] media: Add an API to manage entity enumerations

2015-12-12 Thread Mauro Carvalho Chehab

Hi Sakari,

Em Sun, 29 Nov 2015 21:20:04 +0200
Sakari Ailus  escreveu:

> From: Sakari Ailus 
> 
> This is useful in e.g. knowing whether certain operations have already
> been performed for an entity. The users include the framework itself (for
> graph walking) and a number of drivers.

Please use better names on the vars. See below for details.

> 
> Signed-off-by: Sakari Ailus 
> ---
>  drivers/media/media-entity.c |  39 +
>  include/media/media-device.h |  14 +
>  include/media/media-entity.h | 136 
> ---
>  3 files changed, 181 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
> index d11f440..fceaf44 100644
> --- a/drivers/media/media-entity.c
> +++ b/drivers/media/media-entity.c
> @@ -213,6 +213,45 @@ void media_gobj_remove(struct media_gobj *gobj)
>  }
>  
>  /**
> + * __media_entity_enum_init - Initialise an entity enumeration
> + *
> + * @e: Entity enumeration to be initialised
> + * @idx_max: Maximum number of entities in the enumeration
> + *
> + * Returns zero on success or a negative error code.
> + */

We're using kernel-doc macros only at the header files. Please
move those macros to there.

> +int __media_entity_enum_init(struct media_entity_enum *e, int idx_max)

using "e" as a var is not nice, specially on a public header.

I would use "ent_enum" instead for media_entity_enum pointers. This
applies everywhere on this patch series.

> +{
> + if (idx_max > MEDIA_ENTITY_ENUM_MAX_ID) {
> + e->e = kcalloc(DIV_ROUND_UP(idx_max, BITS_PER_LONG),
> +sizeof(long), GFP_KERNEL);
> + if (!e->e)
> + return -ENOMEM;
> + } else {
> + e->e = e->__e;

This is crap! I can't tell what the above code is doing,
as the var names don't give any clue!

> + }
> +
> + bitmap_zero(e->e, idx_max);

Ok, here, there's a hint that one of the "e" is a bitmap, while
the other is a struct... Weird, and very easy to do wrong things!

Please name the bitmap as "ent_enum_bmap" or something like that.

> + e->idx_max = idx_max;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(__media_entity_enum_init);
> +
> +/**
> + * media_entity_enum_cleanup - Release resources of an entity enumeration
> + *
> + * @e: Entity enumeration to be released
> + */
> +void media_entity_enum_cleanup(struct media_entity_enum *e)
> +{
> + if (e->e != e->__e)
> + kfree(e->e);
> + e->e = NULL;
> +}
> +EXPORT_SYMBOL_GPL(media_entity_enum_cleanup);
> +
> +/**
>   * media_entity_init - Initialize a media entity
>   *
>   * @num_pads: Total number of sink and source pads.
> diff --git a/include/media/media-device.h b/include/media/media-device.h
> index c0e1764..2d46c66 100644
> --- a/include/media/media-device.h
> +++ b/include/media/media-device.h
> @@ -110,6 +110,20 @@ struct media_device {
>  /* media_devnode to media_device */
>  #define to_media_device(node) container_of(node, struct media_device, 
> devnode)
>  
> +/**
> + * media_entity_enum_init - Initialise an entity enumeration
> + *
> + * @e: Entity enumeration to be initialised
> + * @mdev: The related media device
> + *
> + * Returns zero on success or a negative error code.
> + */
> +static inline __must_check int media_entity_enum_init(
> + struct media_entity_enum *e, struct media_device *mdev)
> +{
> + return __media_entity_enum_init(e, mdev->entity_internal_idx_max + 1);
> +}
> +
>  void media_device_init(struct media_device *mdev);
>  void media_device_cleanup(struct media_device *mdev);
>  int __must_check __media_device_register(struct media_device *mdev,
> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> index d3d3a39..5a0339a 100644
> --- a/include/media/media-entity.h
> +++ b/include/media/media-entity.h
> @@ -23,7 +23,7 @@
>  #ifndef _MEDIA_ENTITY_H
>  #define _MEDIA_ENTITY_H
>  
> -#include 
> +#include 
>  #include 
>  #include 
>  #include 
> @@ -71,6 +71,30 @@ struct media_gobj {
>   struct list_headlist;
>  };
>  
> +#define MEDIA_ENTITY_ENUM_MAX_DEPTH  16
> +#define MEDIA_ENTITY_ENUM_MAX_ID 64
> +
> +/*
> + * The number of pads can't be bigger than the number of entities,
> + * as the worse-case scenario is to have one entity linked up to
> + * MEDIA_ENTITY_ENUM_MAX_ID - 1 entities.
> + */
> +#define MEDIA_ENTITY_MAX_PADS(MEDIA_ENTITY_ENUM_MAX_ID - 1)
> +
> +/* struct media_entity_enum - An enumeration of media entities.
> + *
> + * @__e: Pre-allocated space reserved for media entities if the total
> + *   number of entities  does not exceed MEDIA_ENTITY_ENUM_MAX_ID.
> + * @e:   Bit mask in which each bit represents one entity at 
> struct
> + *   media_entity->internal_idx.
> + * @idx_max: Number of bits in the enum.
> + */
> +struct media_entity_enum {
> +

Re: [PATCH v2 03/22] media: Add an API to manage entity enumerations

Re: [PATCH v2 03/22] media: Add an API to manage entity enumerations

Re: [PATCH v2 03/22] media: Add an API to manage entity enumerations

Re: [PATCH v2 03/22] media: Add an API to manage entity enumerations

Re: [PATCH v2 03/22] media: Add an API to manage entity enumerations

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