diff mbox series

[v8,13/53] media: Report the maximum possible number of buffers for the queue

Message ID 20230927153558.159278-14-benjamin.gaignard@collabora.com
State New
Headers
Series Add DELETE_BUF ioctl |

Commit Message

Benjamin Gaignard Sept. 27, 2023, 3:35 p.m. UTC 
  Use one of the struct v4l2_create_buffers reserved bytes to report
the maximum possible number of buffers for the queue.
V4l2 framework set V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS flags in queue
capabilities so userland can know when the field is valid.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
---
 .../userspace-api/media/v4l/vidioc-create-bufs.rst       | 8 ++++++--
 Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst | 1 +
 drivers/media/common/videobuf2/videobuf2-v4l2.c          | 9 +++++++--
 drivers/media/v4l2-core/v4l2-ioctl.c                     | 4 ++--
 include/uapi/linux/videodev2.h                           | 7 ++++++-
 5 files changed, 22 insertions(+), 7 deletions(-)

Comments

Hans Verkuil Oct. 2, 2023, 1:37 p.m. UTC | #1 
On 27/09/2023 17:35, Benjamin Gaignard wrote:
> Use one of the struct v4l2_create_buffers reserved bytes to report
> the maximum possible number of buffers for the queue.
> V4l2 framework set V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS flags in queue
> capabilities so userland can know when the field is valid.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> ---
>  .../userspace-api/media/v4l/vidioc-create-bufs.rst       | 8 ++++++--
>  Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst | 1 +
>  drivers/media/common/videobuf2/videobuf2-v4l2.c          | 9 +++++++--
>  drivers/media/v4l2-core/v4l2-ioctl.c                     | 4 ++--
>  include/uapi/linux/videodev2.h                           | 7 ++++++-
>  5 files changed, 22 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
> index a048a9f6b7b6..1a46549e7462 100644
> --- a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
> +++ b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
> @@ -116,9 +116,13 @@ than the number requested.
>        - ``flags``
>        - Specifies additional buffer management attributes.
>  	See :ref:`memory-flags`.
> -
>      * - __u32
> -      - ``reserved``\ [6]
> +      - ``max_buffers``
> +      - If V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS capability flag is set
> +        this field indicate the maximum possible number of buffers
> +        for this queue.
> +    * - __u32
> +      - ``reserved``\ [5]
>        - A place holder for future extensions. Drivers and applications
>  	must set the array to zero.
>  
> diff --git a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
> index 099fa6695167..0395187e1a5a 100644
> --- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
> +++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
> @@ -120,6 +120,7 @@ aborting or finishing any DMA in progress, an implicit
>  .. _V4L2-BUF-CAP-SUPPORTS-ORPHANED-BUFS:
>  .. _V4L2-BUF-CAP-SUPPORTS-M2M-HOLD-CAPTURE-BUF:
>  .. _V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS:
> +.. _V4L2-BUF-CAP-SUPPORTS-SET-MAX-BUFS:
>  
>  .. raw:: latex
>  
> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> index 278ea1107b01..655133f1ae2b 100644
> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> @@ -686,6 +686,7 @@ EXPORT_SYMBOL(vb2_querybuf);
>  static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
>  {
>  	*caps = V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
> +	*caps |= V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS;
>  	if (q->io_modes & VB2_MMAP)
>  		*caps |= V4L2_BUF_CAP_SUPPORTS_MMAP;
>  	if (q->io_modes & VB2_USERPTR)
> @@ -767,9 +768,13 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
>  
>  	fill_buf_caps(q, &create->capabilities);
>  	validate_memory_flags(q, create->memory, &create->flags);
> -	create->index = q->num_buffers;
> -	if (create->count == 0)
> +
> +	create->max_buffers = q->max_num_buffers;
> +
> +	if (create->count == 0) {
> +		create->index = vb2_get_num_buffers(q);

This breaks git bisect: this function isn't introduced until patch 21/53.

Note: with the build scripts you can just run it with:

./build.sh -patches 53 ...

and it will apply each patch in sequence and attempt to compile it.

Regards,

	Hans

>  		return ret != -EBUSY ? ret : 0;
> +	}
>  
>  	switch (f->type) {
>  	case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index f4d9d6279094..700db197e371 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -483,9 +483,9 @@ static void v4l_print_create_buffers(const void *arg, bool write_only)
>  {
>  	const struct v4l2_create_buffers *p = arg;
>  
> -	pr_cont("index=%d, count=%d, memory=%s, capabilities=0x%08x, ",
> +	pr_cont("index=%d, count=%d, memory=%s, capabilities=0x%08x, max buffers=%u",
>  		p->index, p->count, prt_names(p->memory, v4l2_memory_names),
> -		p->capabilities);
> +		p->capabilities, p->max_buffers);
>  	v4l_print_format(&p->format, write_only);
>  }
>  
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 78260e5d9985..b0dbb1be728c 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -1034,6 +1034,7 @@ struct v4l2_requestbuffers {
>  #define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS		(1 << 4)
>  #define V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF	(1 << 5)
>  #define V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS		(1 << 6)
> +#define V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS		(1 << 7)
>  
>  /**
>   * struct v4l2_plane - plane info for multi-planar buffers
> @@ -2604,6 +2605,9 @@ struct v4l2_dbg_chip_info {
>   * @flags:	additional buffer management attributes (ignored unless the
>   *		queue has V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS capability
>   *		and configured for MMAP streaming I/O).
> + * @max_buffers: if V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS capability flag is set
> + *		 this field indicate the maximum possible number of buffers
> + *		 for this queue.
>   * @reserved:	future extensions
>   */
>  struct v4l2_create_buffers {
> @@ -2613,7 +2617,8 @@ struct v4l2_create_buffers {
>  	struct v4l2_format	format;
>  	__u32			capabilities;
>  	__u32			flags;
> -	__u32			reserved[6];
> +	__u32			max_buffers;
> +	__u32			reserved[5];
>  };
>  
>  /*
Benjamin Gaignard Oct. 2, 2023, 1:46 p.m. UTC | #2 
Le 02/10/2023 à 15:37, Hans Verkuil a écrit :
> On 27/09/2023 17:35, Benjamin Gaignard wrote:
>> Use one of the struct v4l2_create_buffers reserved bytes to report
>> the maximum possible number of buffers for the queue.
>> V4l2 framework set V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS flags in queue
>> capabilities so userland can know when the field is valid.
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
>> ---
>>   .../userspace-api/media/v4l/vidioc-create-bufs.rst       | 8 ++++++--
>>   Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst | 1 +
>>   drivers/media/common/videobuf2/videobuf2-v4l2.c          | 9 +++++++--
>>   drivers/media/v4l2-core/v4l2-ioctl.c                     | 4 ++--
>>   include/uapi/linux/videodev2.h                           | 7 ++++++-
>>   5 files changed, 22 insertions(+), 7 deletions(-)
>>
>> diff --git a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
>> index a048a9f6b7b6..1a46549e7462 100644
>> --- a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
>> +++ b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
>> @@ -116,9 +116,13 @@ than the number requested.
>>         - ``flags``
>>         - Specifies additional buffer management attributes.
>>   	See :ref:`memory-flags`.
>> -
>>       * - __u32
>> -      - ``reserved``\ [6]
>> +      - ``max_buffers``
>> +      - If V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS capability flag is set
>> +        this field indicate the maximum possible number of buffers
>> +        for this queue.
>> +    * - __u32
>> +      - ``reserved``\ [5]
>>         - A place holder for future extensions. Drivers and applications
>>   	must set the array to zero.
>>   
>> diff --git a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
>> index 099fa6695167..0395187e1a5a 100644
>> --- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
>> +++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
>> @@ -120,6 +120,7 @@ aborting or finishing any DMA in progress, an implicit
>>   .. _V4L2-BUF-CAP-SUPPORTS-ORPHANED-BUFS:
>>   .. _V4L2-BUF-CAP-SUPPORTS-M2M-HOLD-CAPTURE-BUF:
>>   .. _V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS:
>> +.. _V4L2-BUF-CAP-SUPPORTS-SET-MAX-BUFS:
>>   
>>   .. raw:: latex
>>   
>> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
>> index 278ea1107b01..655133f1ae2b 100644
>> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
>> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
>> @@ -686,6 +686,7 @@ EXPORT_SYMBOL(vb2_querybuf);
>>   static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
>>   {
>>   	*caps = V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
>> +	*caps |= V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS;
>>   	if (q->io_modes & VB2_MMAP)
>>   		*caps |= V4L2_BUF_CAP_SUPPORTS_MMAP;
>>   	if (q->io_modes & VB2_USERPTR)
>> @@ -767,9 +768,13 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
>>   
>>   	fill_buf_caps(q, &create->capabilities);
>>   	validate_memory_flags(q, create->memory, &create->flags);
>> -	create->index = q->num_buffers;
>> -	if (create->count == 0)
>> +
>> +	create->max_buffers = q->max_num_buffers;
>> +
>> +	if (create->count == 0) {
>> +		create->index = vb2_get_num_buffers(q);
> This breaks git bisect: this function isn't introduced until patch 21/53.
>
> Note: with the build scripts you can just run it with:
>
> ./build.sh -patches 53 ...
>
> and it will apply each patch in sequence and attempt to compile it.

It should  be create->index = q->num_buffers;
The error is also in v9...

>
> Regards,
>
> 	Hans
>
>>   		return ret != -EBUSY ? ret : 0;
>> +	}
>>   
>>   	switch (f->type) {
>>   	case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
>> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
>> index f4d9d6279094..700db197e371 100644
>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>> @@ -483,9 +483,9 @@ static void v4l_print_create_buffers(const void *arg, bool write_only)
>>   {
>>   	const struct v4l2_create_buffers *p = arg;
>>   
>> -	pr_cont("index=%d, count=%d, memory=%s, capabilities=0x%08x, ",
>> +	pr_cont("index=%d, count=%d, memory=%s, capabilities=0x%08x, max buffers=%u",
>>   		p->index, p->count, prt_names(p->memory, v4l2_memory_names),
>> -		p->capabilities);
>> +		p->capabilities, p->max_buffers);
>>   	v4l_print_format(&p->format, write_only);
>>   }
>>   
>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>> index 78260e5d9985..b0dbb1be728c 100644
>> --- a/include/uapi/linux/videodev2.h
>> +++ b/include/uapi/linux/videodev2.h
>> @@ -1034,6 +1034,7 @@ struct v4l2_requestbuffers {
>>   #define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS		(1 << 4)
>>   #define V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF	(1 << 5)
>>   #define V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS		(1 << 6)
>> +#define V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS		(1 << 7)
>>   
>>   /**
>>    * struct v4l2_plane - plane info for multi-planar buffers
>> @@ -2604,6 +2605,9 @@ struct v4l2_dbg_chip_info {
>>    * @flags:	additional buffer management attributes (ignored unless the
>>    *		queue has V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS capability
>>    *		and configured for MMAP streaming I/O).
>> + * @max_buffers: if V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS capability flag is set
>> + *		 this field indicate the maximum possible number of buffers
>> + *		 for this queue.
>>    * @reserved:	future extensions
>>    */
>>   struct v4l2_create_buffers {
>> @@ -2613,7 +2617,8 @@ struct v4l2_create_buffers {
>>   	struct v4l2_format	format;
>>   	__u32			capabilities;
>>   	__u32			flags;
>> -	__u32			reserved[6];
>> +	__u32			max_buffers;
>> +	__u32			reserved[5];
>>   };
>>   
>>   /*
>
Hans Verkuil Oct. 2, 2023, 1:49 p.m. UTC | #3 
On 02/10/2023 15:46, Benjamin Gaignard wrote:
> 
> Le 02/10/2023 à 15:37, Hans Verkuil a écrit :
>> On 27/09/2023 17:35, Benjamin Gaignard wrote:
>>> Use one of the struct v4l2_create_buffers reserved bytes to report
>>> the maximum possible number of buffers for the queue.
>>> V4l2 framework set V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS flags in queue
>>> capabilities so userland can know when the field is valid.
>>>
>>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
>>> ---
>>>   .../userspace-api/media/v4l/vidioc-create-bufs.rst       | 8 ++++++--
>>>   Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst | 1 +
>>>   drivers/media/common/videobuf2/videobuf2-v4l2.c          | 9 +++++++--
>>>   drivers/media/v4l2-core/v4l2-ioctl.c                     | 4 ++--
>>>   include/uapi/linux/videodev2.h                           | 7 ++++++-
>>>   5 files changed, 22 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
>>> index a048a9f6b7b6..1a46549e7462 100644
>>> --- a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
>>> +++ b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
>>> @@ -116,9 +116,13 @@ than the number requested.
>>>         - ``flags``
>>>         - Specifies additional buffer management attributes.
>>>       See :ref:`memory-flags`.
>>> -
>>>       * - __u32
>>> -      - ``reserved``\ [6]
>>> +      - ``max_buffers``
>>> +      - If V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS capability flag is set
>>> +        this field indicate the maximum possible number of buffers
>>> +        for this queue.
>>> +    * - __u32
>>> +      - ``reserved``\ [5]
>>>         - A place holder for future extensions. Drivers and applications
>>>       must set the array to zero.
>>>   diff --git a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
>>> index 099fa6695167..0395187e1a5a 100644
>>> --- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
>>> +++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
>>> @@ -120,6 +120,7 @@ aborting or finishing any DMA in progress, an implicit
>>>   .. _V4L2-BUF-CAP-SUPPORTS-ORPHANED-BUFS:
>>>   .. _V4L2-BUF-CAP-SUPPORTS-M2M-HOLD-CAPTURE-BUF:
>>>   .. _V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS:
>>> +.. _V4L2-BUF-CAP-SUPPORTS-SET-MAX-BUFS:
>>>     .. raw:: latex
>>>   diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
>>> index 278ea1107b01..655133f1ae2b 100644
>>> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
>>> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
>>> @@ -686,6 +686,7 @@ EXPORT_SYMBOL(vb2_querybuf);
>>>   static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
>>>   {
>>>       *caps = V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
>>> +    *caps |= V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS;
>>>       if (q->io_modes & VB2_MMAP)
>>>           *caps |= V4L2_BUF_CAP_SUPPORTS_MMAP;
>>>       if (q->io_modes & VB2_USERPTR)
>>> @@ -767,9 +768,13 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
>>>         fill_buf_caps(q, &create->capabilities);
>>>       validate_memory_flags(q, create->memory, &create->flags);
>>> -    create->index = q->num_buffers;
>>> -    if (create->count == 0)
>>> +
>>> +    create->max_buffers = q->max_num_buffers;
>>> +
>>> +    if (create->count == 0) {
>>> +        create->index = vb2_get_num_buffers(q);
>> This breaks git bisect: this function isn't introduced until patch 21/53.
>>
>> Note: with the build scripts you can just run it with:
>>
>> ./build.sh -patches 53 ...
>>
>> and it will apply each patch in sequence and attempt to compile it.
> 
> It should  be create->index = q->num_buffers;
> The error is also in v9...

Sorry, I meant to reply to the v9 patch, so yes, it is also in v9 :-)

	Hans

> 
>>
>> Regards,
>>
>>     Hans
>>
>>>           return ret != -EBUSY ? ret : 0;
>>> +    }
>>>         switch (f->type) {
>>>       case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
>>> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
>>> index f4d9d6279094..700db197e371 100644
>>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>>> @@ -483,9 +483,9 @@ static void v4l_print_create_buffers(const void *arg, bool write_only)
>>>   {
>>>       const struct v4l2_create_buffers *p = arg;
>>>   -    pr_cont("index=%d, count=%d, memory=%s, capabilities=0x%08x, ",
>>> +    pr_cont("index=%d, count=%d, memory=%s, capabilities=0x%08x, max buffers=%u",
>>>           p->index, p->count, prt_names(p->memory, v4l2_memory_names),
>>> -        p->capabilities);
>>> +        p->capabilities, p->max_buffers);
>>>       v4l_print_format(&p->format, write_only);
>>>   }
>>>   diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>>> index 78260e5d9985..b0dbb1be728c 100644
>>> --- a/include/uapi/linux/videodev2.h
>>> +++ b/include/uapi/linux/videodev2.h
>>> @@ -1034,6 +1034,7 @@ struct v4l2_requestbuffers {
>>>   #define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS        (1 << 4)
>>>   #define V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF    (1 << 5)
>>>   #define V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS        (1 << 6)
>>> +#define V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS        (1 << 7)
>>>     /**
>>>    * struct v4l2_plane - plane info for multi-planar buffers
>>> @@ -2604,6 +2605,9 @@ struct v4l2_dbg_chip_info {
>>>    * @flags:    additional buffer management attributes (ignored unless the
>>>    *        queue has V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS capability
>>>    *        and configured for MMAP streaming I/O).
>>> + * @max_buffers: if V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS capability flag is set
>>> + *         this field indicate the maximum possible number of buffers
>>> + *         for this queue.
>>>    * @reserved:    future extensions
>>>    */
>>>   struct v4l2_create_buffers {
>>> @@ -2613,7 +2617,8 @@ struct v4l2_create_buffers {
>>>       struct v4l2_format    format;
>>>       __u32            capabilities;
>>>       __u32            flags;
>>> -    __u32            reserved[6];
>>> +    __u32            max_buffers;
>>> +    __u32            reserved[5];
>>>   };
>>>     /*
>>
diff mbox series

Patch

diff --git a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
index a048a9f6b7b6..1a46549e7462 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
@@ -116,9 +116,13 @@  than the number requested.
       - ``flags``
       - Specifies additional buffer management attributes.
 	See :ref:`memory-flags`.
-
     * - __u32
-      - ``reserved``\ [6]
+      - ``max_buffers``
+      - If V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS capability flag is set
+        this field indicate the maximum possible number of buffers
+        for this queue.
+    * - __u32
+      - ``reserved``\ [5]
       - A place holder for future extensions. Drivers and applications
 	must set the array to zero.
 
diff --git a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
index 099fa6695167..0395187e1a5a 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
@@ -120,6 +120,7 @@  aborting or finishing any DMA in progress, an implicit
 .. _V4L2-BUF-CAP-SUPPORTS-ORPHANED-BUFS:
 .. _V4L2-BUF-CAP-SUPPORTS-M2M-HOLD-CAPTURE-BUF:
 .. _V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS:
+.. _V4L2-BUF-CAP-SUPPORTS-SET-MAX-BUFS:
 
 .. raw:: latex
 
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 278ea1107b01..655133f1ae2b 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -686,6 +686,7 @@  EXPORT_SYMBOL(vb2_querybuf);
 static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
 {
 	*caps = V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
+	*caps |= V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS;
 	if (q->io_modes & VB2_MMAP)
 		*caps |= V4L2_BUF_CAP_SUPPORTS_MMAP;
 	if (q->io_modes & VB2_USERPTR)
@@ -767,9 +768,13 @@  int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
 
 	fill_buf_caps(q, &create->capabilities);
 	validate_memory_flags(q, create->memory, &create->flags);
-	create->index = q->num_buffers;
-	if (create->count == 0)
+
+	create->max_buffers = q->max_num_buffers;
+
+	if (create->count == 0) {
+		create->index = vb2_get_num_buffers(q);
 		return ret != -EBUSY ? ret : 0;
+	}
 
 	switch (f->type) {
 	case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index f4d9d6279094..700db197e371 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -483,9 +483,9 @@  static void v4l_print_create_buffers(const void *arg, bool write_only)
 {
 	const struct v4l2_create_buffers *p = arg;
 
-	pr_cont("index=%d, count=%d, memory=%s, capabilities=0x%08x, ",
+	pr_cont("index=%d, count=%d, memory=%s, capabilities=0x%08x, max buffers=%u",
 		p->index, p->count, prt_names(p->memory, v4l2_memory_names),
-		p->capabilities);
+		p->capabilities, p->max_buffers);
 	v4l_print_format(&p->format, write_only);
 }
 
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 78260e5d9985..b0dbb1be728c 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -1034,6 +1034,7 @@  struct v4l2_requestbuffers {
 #define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS		(1 << 4)
 #define V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF	(1 << 5)
 #define V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS		(1 << 6)
+#define V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS		(1 << 7)
 
 /**
  * struct v4l2_plane - plane info for multi-planar buffers
@@ -2604,6 +2605,9 @@  struct v4l2_dbg_chip_info {
  * @flags:	additional buffer management attributes (ignored unless the
  *		queue has V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS capability
  *		and configured for MMAP streaming I/O).
+ * @max_buffers: if V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS capability flag is set
+ *		 this field indicate the maximum possible number of buffers
+ *		 for this queue.
  * @reserved:	future extensions
  */
 struct v4l2_create_buffers {
@@ -2613,7 +2617,8 @@  struct v4l2_create_buffers {
 	struct v4l2_format	format;
 	__u32			capabilities;
 	__u32			flags;
-	__u32			reserved[6];
+	__u32			max_buffers;
+	__u32			reserved[5];
 };
 
 /*