diff mbox series

[PATCHv4,6/8] videobuf2: add queue memory coherency parameter

Message ID 20210727070517.443167-7-senozhatsky@chromium.org
State Superseded
Headers show
Series videobuf2: support new noncontiguous DMA API | expand

Commit Message

Sergey Senozhatsky July 27, 2021, 7:05 a.m. UTC
Preparations for future V4L2_MEMORY_FLAG_NON_COHERENT support.

Extend vb2_core_reqbufs() parameters list to accept requests'
->flags, which will be used for memory coherency configuration.

An attempt to allocate a buffer with coherency requirements
which don't match queue's consistency model will fail.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
 .../media/common/videobuf2/videobuf2-core.c   | 38 ++++++++++++++++---
 .../media/common/videobuf2/videobuf2-v4l2.c   |  5 ++-
 drivers/media/dvb-core/dvb_vb2.c              |  2 +-
 include/media/videobuf2-core.h                | 10 ++++-
 4 files changed, 44 insertions(+), 11 deletions(-)

Comments

Hans Verkuil Aug. 3, 2021, 8:29 a.m. UTC | #1
On 27/07/2021 09:05, Sergey Senozhatsky wrote:
> Preparations for future V4L2_MEMORY_FLAG_NON_COHERENT support.

> 

> Extend vb2_core_reqbufs() parameters list to accept requests'


Extend -> Extend the

> ->flags, which will be used for memory coherency configuration.

> 

> An attempt to allocate a buffer with coherency requirements

> which don't match queue's consistency model will fail.


which don't match -> that do not match the

> 

> Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>

> ---

>  .../media/common/videobuf2/videobuf2-core.c   | 38 ++++++++++++++++---

>  .../media/common/videobuf2/videobuf2-v4l2.c   |  5 ++-

>  drivers/media/dvb-core/dvb_vb2.c              |  2 +-

>  include/media/videobuf2-core.h                | 10 ++++-

>  4 files changed, 44 insertions(+), 11 deletions(-)

> 

> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c

> index 55af63d54f23..af4db310cf5e 100644

> --- a/drivers/media/common/videobuf2/videobuf2-core.c

> +++ b/drivers/media/common/videobuf2/videobuf2-core.c

> @@ -738,11 +738,31 @@ int vb2_verify_memory_type(struct vb2_queue *q,

>  }

>  EXPORT_SYMBOL(vb2_verify_memory_type);

>  

> +static void set_queue_coherency(struct vb2_queue *q, bool coherent_mem)

> +{

> +	q->coherent_mem = 1;


This I do not like: coherent memory is the default, and so I think it will
be more robust if this field is renamed to non_coherent_mem and so coherent
memory will be the default since this field will be cleared initially with
kzalloc.

Basically a similar argument that you used in patch 2/8.

I also think that it improves readability, since non-coherent is the
exceptional case, not the rule, and the field name corresponds with the
V4L2 memory flag name.

I noticed that in v1 of this series it was actually called non_coherent_mem,
and it was changed in v2, actually after some comments from me.

But I changed my mind on that, and I think it makes more sense to go back to
calling this non_coherent_mem.

Regards,

	Hans

> +

> +	if (!vb2_queue_allows_cache_hints(q))

> +		return;

> +	if (!coherent_mem)

> +		q->coherent_mem = 0;

> +}

> +

> +static bool verify_coherency_flags(struct vb2_queue *q, bool coherent_mem)

> +{

> +	if (coherent_mem != q->coherent_mem) {

> +		dprintk(q, 1, "memory coherency model mismatch\n");

> +		return false;

> +	}

> +	return true;

> +}

> +

>  int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,

> -		     unsigned int *count)

> +		     unsigned int flags, unsigned int *count)

>  {

>  	unsigned int num_buffers, allocated_buffers, num_planes = 0;

>  	unsigned plane_sizes[VB2_MAX_PLANES] = { };

> +	bool coherent_mem = true;

>  	unsigned int i;

>  	int ret;

>  

> @@ -757,7 +777,8 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,

>  	}

>  

>  	if (*count == 0 || q->num_buffers != 0 ||

> -	    (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory)) {

> +	    (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory) ||

> +	    !verify_coherency_flags(q, coherent_mem)) {

>  		/*

>  		 * We already have buffers allocated, so first check if they

>  		 * are not in use and can be freed.

> @@ -794,6 +815,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,

>  	num_buffers = min_t(unsigned int, num_buffers, VB2_MAX_FRAME);

>  	memset(q->alloc_devs, 0, sizeof(q->alloc_devs));

>  	q->memory = memory;

> +	set_queue_coherency(q, coherent_mem);

>  

>  	/*

>  	 * Ask the driver how many buffers and planes per buffer it requires.

> @@ -878,12 +900,13 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,

>  EXPORT_SYMBOL_GPL(vb2_core_reqbufs);

>  

>  int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,

> -			 unsigned int *count,

> +			 unsigned int flags, unsigned int *count,

>  			 unsigned int requested_planes,

>  			 const unsigned int requested_sizes[])

>  {

>  	unsigned int num_planes = 0, num_buffers, allocated_buffers;

>  	unsigned plane_sizes[VB2_MAX_PLANES] = { };

> +	bool coherent_mem = true;

>  	int ret;

>  

>  	if (q->num_buffers == VB2_MAX_FRAME) {

> @@ -899,11 +922,14 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,

>  		memset(q->alloc_devs, 0, sizeof(q->alloc_devs));

>  		q->memory = memory;

>  		q->waiting_for_buffers = !q->is_output;

> +		set_queue_coherency(q, coherent_mem);

>  	} else {

>  		if (q->memory != memory) {

>  			dprintk(q, 1, "memory model mismatch\n");

>  			return -EINVAL;

>  		}

> +		if (!verify_coherency_flags(q, coherent_mem))

> +			return -EINVAL;

>  	}

>  

>  	num_buffers = min(*count, VB2_MAX_FRAME - q->num_buffers);

> @@ -2576,7 +2602,7 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)

>  	fileio->memory = VB2_MEMORY_MMAP;

>  	fileio->type = q->type;

>  	q->fileio = fileio;

> -	ret = vb2_core_reqbufs(q, fileio->memory, &fileio->count);

> +	ret = vb2_core_reqbufs(q, fileio->memory, 0, &fileio->count);

>  	if (ret)

>  		goto err_kfree;

>  

> @@ -2633,7 +2659,7 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)

>  

>  err_reqbufs:

>  	fileio->count = 0;

> -	vb2_core_reqbufs(q, fileio->memory, &fileio->count);

> +	vb2_core_reqbufs(q, fileio->memory, 0, &fileio->count);

>  

>  err_kfree:

>  	q->fileio = NULL;

> @@ -2653,7 +2679,7 @@ static int __vb2_cleanup_fileio(struct vb2_queue *q)

>  		vb2_core_streamoff(q, q->type);

>  		q->fileio = NULL;

>  		fileio->count = 0;

> -		vb2_core_reqbufs(q, fileio->memory, &fileio->count);

> +		vb2_core_reqbufs(q, fileio->memory, 0, &fileio->count);

>  		kfree(fileio);

>  		dprintk(q, 3, "file io emulator closed\n");

>  	}

> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c

> index 2fbae9bd7b52..b4f70ddb09b0 100644

> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c

> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c

> @@ -697,7 +697,7 @@ int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)

>  	int ret = vb2_verify_memory_type(q, req->memory, req->type);

>  

>  	fill_buf_caps(q, &req->capabilities);

> -	return ret ? ret : vb2_core_reqbufs(q, req->memory, &req->count);

> +	return ret ? ret : vb2_core_reqbufs(q, req->memory, 0, &req->count);

>  }

>  EXPORT_SYMBOL_GPL(vb2_reqbufs);

>  

> @@ -772,6 +772,7 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)

>  		if (requested_sizes[i] == 0)

>  			return -EINVAL;

>  	return ret ? ret : vb2_core_create_bufs(q, create->memory,

> +						0,

>  						&create->count,

>  						requested_planes,

>  						requested_sizes);

> @@ -974,7 +975,7 @@ int vb2_ioctl_reqbufs(struct file *file, void *priv,

>  		return res;

>  	if (vb2_queue_is_busy(vdev, file))

>  		return -EBUSY;

> -	res = vb2_core_reqbufs(vdev->queue, p->memory, &p->count);

> +	res = vb2_core_reqbufs(vdev->queue, p->memory, 0, &p->count);

>  	/* If count == 0, then the owner has released all buffers and he

>  	   is no longer owner of the queue. Otherwise we have a new owner. */

>  	if (res == 0)

> diff --git a/drivers/media/dvb-core/dvb_vb2.c b/drivers/media/dvb-core/dvb_vb2.c

> index 6974f1731529..959d110407a4 100644

> --- a/drivers/media/dvb-core/dvb_vb2.c

> +++ b/drivers/media/dvb-core/dvb_vb2.c

> @@ -342,7 +342,7 @@ int dvb_vb2_reqbufs(struct dvb_vb2_ctx *ctx, struct dmx_requestbuffers *req)

>  

>  	ctx->buf_siz = req->size;

>  	ctx->buf_cnt = req->count;

> -	ret = vb2_core_reqbufs(&ctx->vb_q, VB2_MEMORY_MMAP, &req->count);

> +	ret = vb2_core_reqbufs(&ctx->vb_q, VB2_MEMORY_MMAP, 0, &req->count);

>  	if (ret) {

>  		ctx->state = DVB_VB2_STATE_NONE;

>  		dprintk(1, "[%s] count=%d size=%d errno=%d\n", ctx->name,

> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h

> index 66e548268242..7e748cd09b7a 100644

> --- a/include/media/videobuf2-core.h

> +++ b/include/media/videobuf2-core.h

> @@ -504,6 +504,8 @@ struct vb2_buf_ops {

>   * @allow_cache_hints: when set user-space can pass cache management hints in

>   *		order to skip cache flush/invalidation on ->prepare() or/and

>   *		->finish().

> + * @coherent_mem: when cleared queue will attempt to allocate buffers using

> + *		non-coherent memory.

>   * @lock:	pointer to a mutex that protects the &struct vb2_queue. The

>   *		driver can set this to a mutex to let the v4l2 core serialize

>   *		the queuing ioctls. If the driver wants to handle locking

> @@ -583,6 +585,7 @@ struct vb2_queue {

>  	unsigned int			uses_qbuf:1;

>  	unsigned int			uses_requests:1;

>  	unsigned int			allow_cache_hints:1;

> +	unsigned int			coherent_mem:1;

>  

>  	struct mutex			*lock;

>  	void				*owner;

> @@ -748,6 +751,8 @@ void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb);

>   * vb2_core_reqbufs() - Initiate streaming.

>   * @q:		pointer to &struct vb2_queue with videobuf2 queue.

>   * @memory:	memory type, as defined by &enum vb2_memory.

> + * @flags:	auxiliary queue/buffer management flags. Currently, the only

> + *		used flag is %V4L2_MEMORY_FLAG_NON_COHERENT.

>   * @count:	requested buffer count.

>   *

>   * Videobuf2 core helper to implement VIDIOC_REQBUF() operation. It is called

> @@ -772,12 +777,13 @@ void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb);

>   * Return: returns zero on success; an error code otherwise.

>   */

>  int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,

> -		    unsigned int *count);

> +		     unsigned int flags, unsigned int *count);

>  

>  /**

>   * vb2_core_create_bufs() - Allocate buffers and any required auxiliary structs

>   * @q: pointer to &struct vb2_queue with videobuf2 queue.

>   * @memory: memory type, as defined by &enum vb2_memory.

> + * @flags: auxiliary queue/buffer management flags.

>   * @count: requested buffer count.

>   * @requested_planes: number of planes requested.

>   * @requested_sizes: array with the size of the planes.

> @@ -795,7 +801,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,

>   * Return: returns zero on success; an error code otherwise.

>   */

>  int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,

> -			 unsigned int *count,

> +			 unsigned int flags, unsigned int *count,

>  			 unsigned int requested_planes,

>  			 const unsigned int requested_sizes[]);

>  

>
Sergey Senozhatsky Aug. 17, 2021, 10:43 a.m. UTC | #2
On (21/08/03 10:29), Hans Verkuil wrote:
> >  

> > +static void set_queue_coherency(struct vb2_queue *q, bool coherent_mem)

> > +{

> > +	q->coherent_mem = 1;

> 

> This I do not like: coherent memory is the default, and so I think it will

> be more robust if this field is renamed to non_coherent_mem and so coherent

> memory will be the default since this field will be cleared initially with

> kzalloc.

> 

> Basically a similar argument that you used in patch 2/8.

> 

> I also think that it improves readability, since non-coherent is the

> exceptional case, not the rule, and the field name corresponds with the

> V4L2 memory flag name.

> 

> I noticed that in v1 of this series it was actually called non_coherent_mem,

> and it was changed in v2, actually after some comments from me.

> 

> But I changed my mind on that, and I think it makes more sense to go back to

> calling this non_coherent_mem.


Ok, done. Hans, is this your final decision? :)
diff mbox series

Patch

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 55af63d54f23..af4db310cf5e 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -738,11 +738,31 @@  int vb2_verify_memory_type(struct vb2_queue *q,
 }
 EXPORT_SYMBOL(vb2_verify_memory_type);
 
+static void set_queue_coherency(struct vb2_queue *q, bool coherent_mem)
+{
+	q->coherent_mem = 1;
+
+	if (!vb2_queue_allows_cache_hints(q))
+		return;
+	if (!coherent_mem)
+		q->coherent_mem = 0;
+}
+
+static bool verify_coherency_flags(struct vb2_queue *q, bool coherent_mem)
+{
+	if (coherent_mem != q->coherent_mem) {
+		dprintk(q, 1, "memory coherency model mismatch\n");
+		return false;
+	}
+	return true;
+}
+
 int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
-		     unsigned int *count)
+		     unsigned int flags, unsigned int *count)
 {
 	unsigned int num_buffers, allocated_buffers, num_planes = 0;
 	unsigned plane_sizes[VB2_MAX_PLANES] = { };
+	bool coherent_mem = true;
 	unsigned int i;
 	int ret;
 
@@ -757,7 +777,8 @@  int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 	}
 
 	if (*count == 0 || q->num_buffers != 0 ||
-	    (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory)) {
+	    (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory) ||
+	    !verify_coherency_flags(q, coherent_mem)) {
 		/*
 		 * We already have buffers allocated, so first check if they
 		 * are not in use and can be freed.
@@ -794,6 +815,7 @@  int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 	num_buffers = min_t(unsigned int, num_buffers, VB2_MAX_FRAME);
 	memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
 	q->memory = memory;
+	set_queue_coherency(q, coherent_mem);
 
 	/*
 	 * Ask the driver how many buffers and planes per buffer it requires.
@@ -878,12 +900,13 @@  int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 EXPORT_SYMBOL_GPL(vb2_core_reqbufs);
 
 int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
-			 unsigned int *count,
+			 unsigned int flags, unsigned int *count,
 			 unsigned int requested_planes,
 			 const unsigned int requested_sizes[])
 {
 	unsigned int num_planes = 0, num_buffers, allocated_buffers;
 	unsigned plane_sizes[VB2_MAX_PLANES] = { };
+	bool coherent_mem = true;
 	int ret;
 
 	if (q->num_buffers == VB2_MAX_FRAME) {
@@ -899,11 +922,14 @@  int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 		memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
 		q->memory = memory;
 		q->waiting_for_buffers = !q->is_output;
+		set_queue_coherency(q, coherent_mem);
 	} else {
 		if (q->memory != memory) {
 			dprintk(q, 1, "memory model mismatch\n");
 			return -EINVAL;
 		}
+		if (!verify_coherency_flags(q, coherent_mem))
+			return -EINVAL;
 	}
 
 	num_buffers = min(*count, VB2_MAX_FRAME - q->num_buffers);
@@ -2576,7 +2602,7 @@  static int __vb2_init_fileio(struct vb2_queue *q, int read)
 	fileio->memory = VB2_MEMORY_MMAP;
 	fileio->type = q->type;
 	q->fileio = fileio;
-	ret = vb2_core_reqbufs(q, fileio->memory, &fileio->count);
+	ret = vb2_core_reqbufs(q, fileio->memory, 0, &fileio->count);
 	if (ret)
 		goto err_kfree;
 
@@ -2633,7 +2659,7 @@  static int __vb2_init_fileio(struct vb2_queue *q, int read)
 
 err_reqbufs:
 	fileio->count = 0;
-	vb2_core_reqbufs(q, fileio->memory, &fileio->count);
+	vb2_core_reqbufs(q, fileio->memory, 0, &fileio->count);
 
 err_kfree:
 	q->fileio = NULL;
@@ -2653,7 +2679,7 @@  static int __vb2_cleanup_fileio(struct vb2_queue *q)
 		vb2_core_streamoff(q, q->type);
 		q->fileio = NULL;
 		fileio->count = 0;
-		vb2_core_reqbufs(q, fileio->memory, &fileio->count);
+		vb2_core_reqbufs(q, fileio->memory, 0, &fileio->count);
 		kfree(fileio);
 		dprintk(q, 3, "file io emulator closed\n");
 	}
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 2fbae9bd7b52..b4f70ddb09b0 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -697,7 +697,7 @@  int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 	int ret = vb2_verify_memory_type(q, req->memory, req->type);
 
 	fill_buf_caps(q, &req->capabilities);
-	return ret ? ret : vb2_core_reqbufs(q, req->memory, &req->count);
+	return ret ? ret : vb2_core_reqbufs(q, req->memory, 0, &req->count);
 }
 EXPORT_SYMBOL_GPL(vb2_reqbufs);
 
@@ -772,6 +772,7 @@  int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
 		if (requested_sizes[i] == 0)
 			return -EINVAL;
 	return ret ? ret : vb2_core_create_bufs(q, create->memory,
+						0,
 						&create->count,
 						requested_planes,
 						requested_sizes);
@@ -974,7 +975,7 @@  int vb2_ioctl_reqbufs(struct file *file, void *priv,
 		return res;
 	if (vb2_queue_is_busy(vdev, file))
 		return -EBUSY;
-	res = vb2_core_reqbufs(vdev->queue, p->memory, &p->count);
+	res = vb2_core_reqbufs(vdev->queue, p->memory, 0, &p->count);
 	/* If count == 0, then the owner has released all buffers and he
 	   is no longer owner of the queue. Otherwise we have a new owner. */
 	if (res == 0)
diff --git a/drivers/media/dvb-core/dvb_vb2.c b/drivers/media/dvb-core/dvb_vb2.c
index 6974f1731529..959d110407a4 100644
--- a/drivers/media/dvb-core/dvb_vb2.c
+++ b/drivers/media/dvb-core/dvb_vb2.c
@@ -342,7 +342,7 @@  int dvb_vb2_reqbufs(struct dvb_vb2_ctx *ctx, struct dmx_requestbuffers *req)
 
 	ctx->buf_siz = req->size;
 	ctx->buf_cnt = req->count;
-	ret = vb2_core_reqbufs(&ctx->vb_q, VB2_MEMORY_MMAP, &req->count);
+	ret = vb2_core_reqbufs(&ctx->vb_q, VB2_MEMORY_MMAP, 0, &req->count);
 	if (ret) {
 		ctx->state = DVB_VB2_STATE_NONE;
 		dprintk(1, "[%s] count=%d size=%d errno=%d\n", ctx->name,
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 66e548268242..7e748cd09b7a 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -504,6 +504,8 @@  struct vb2_buf_ops {
  * @allow_cache_hints: when set user-space can pass cache management hints in
  *		order to skip cache flush/invalidation on ->prepare() or/and
  *		->finish().
+ * @coherent_mem: when cleared queue will attempt to allocate buffers using
+ *		non-coherent memory.
  * @lock:	pointer to a mutex that protects the &struct vb2_queue. The
  *		driver can set this to a mutex to let the v4l2 core serialize
  *		the queuing ioctls. If the driver wants to handle locking
@@ -583,6 +585,7 @@  struct vb2_queue {
 	unsigned int			uses_qbuf:1;
 	unsigned int			uses_requests:1;
 	unsigned int			allow_cache_hints:1;
+	unsigned int			coherent_mem:1;
 
 	struct mutex			*lock;
 	void				*owner;
@@ -748,6 +751,8 @@  void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb);
  * vb2_core_reqbufs() - Initiate streaming.
  * @q:		pointer to &struct vb2_queue with videobuf2 queue.
  * @memory:	memory type, as defined by &enum vb2_memory.
+ * @flags:	auxiliary queue/buffer management flags. Currently, the only
+ *		used flag is %V4L2_MEMORY_FLAG_NON_COHERENT.
  * @count:	requested buffer count.
  *
  * Videobuf2 core helper to implement VIDIOC_REQBUF() operation. It is called
@@ -772,12 +777,13 @@  void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb);
  * Return: returns zero on success; an error code otherwise.
  */
 int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
-		    unsigned int *count);
+		     unsigned int flags, unsigned int *count);
 
 /**
  * vb2_core_create_bufs() - Allocate buffers and any required auxiliary structs
  * @q: pointer to &struct vb2_queue with videobuf2 queue.
  * @memory: memory type, as defined by &enum vb2_memory.
+ * @flags: auxiliary queue/buffer management flags.
  * @count: requested buffer count.
  * @requested_planes: number of planes requested.
  * @requested_sizes: array with the size of the planes.
@@ -795,7 +801,7 @@  int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
  * Return: returns zero on success; an error code otherwise.
  */
 int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
-			 unsigned int *count,
+			 unsigned int flags, unsigned int *count,
 			 unsigned int requested_planes,
 			 const unsigned int requested_sizes[]);