Re: [PATCH v3 1/7] media: vb2: Add a helper to get the vb2 buffer attached to a request

[Boris Brezillon <boris.brezillon-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>]

On Fri, 13 Dec 2019 17:09:35 +0200
Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org> wrote:

> Hi Boris,
> 
> On Fri, Dec 13, 2019 at 01:54:08PM +0100, Boris Brezillon wrote:
> > vb2_request_get_buf() returns the N-th buffer attached to a media
> > request.
> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
> > ---
> > Changes in v3:
> > * None
> > 
> > Changes in v2:
> > * Adjust the kernel doc as suggested by Hans
> > ---
> >  .../media/common/videobuf2/videobuf2-core.c   | 23 +++++++++++++++++++
> >  include/media/videobuf2-core.h                | 11 +++++++++
> >  2 files changed, 34 insertions(+)
> > 
> > diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> > index 4489744fbbd9..c4c7980dcb0d 100644
> > --- a/drivers/media/common/videobuf2/videobuf2-core.c
> > +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> > @@ -1416,6 +1416,29 @@ unsigned int vb2_request_buffer_cnt(struct media_request *req)
> >  }
> >  EXPORT_SYMBOL_GPL(vb2_request_buffer_cnt);
> >  
> > +struct vb2_buffer *vb2_request_get_buf(struct media_request *req,
> > +				       unsigned int n)
> > +{
> > +	struct media_request_object *obj;
> > +	struct vb2_buffer *buf = NULL;
> > +	unsigned int nbufs = 0;
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&req->lock, flags);
> > +	list_for_each_entry(obj, &req->objects, list) {
> > +		if (!vb2_request_object_is_buffer(obj) ||
> > +		    nbufs++ < n)
> > +			continue;
> > +
> > +		buf = container_of(obj, struct vb2_buffer, req_obj);
> > +		break;
> > +	}
> > +	spin_unlock_irqrestore(&req->lock, flags);
> > +
> > +	return buf;
> > +}
> > +EXPORT_SYMBOL_GPL(vb2_request_get_buf);
> > +
> >  int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb)
> >  {
> >  	struct vb2_buffer *vb;
> > diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> > index a2b2208b02da..6206e25df764 100644
> > --- a/include/media/videobuf2-core.h
> > +++ b/include/media/videobuf2-core.h
> > @@ -1225,4 +1225,15 @@ bool vb2_request_object_is_buffer(struct media_request_object *obj);
> >   */
> >  unsigned int vb2_request_buffer_cnt(struct media_request *req);
> >  
> > +/**
> > + * vb2_request_get_buf() - return the buffer at index @idx
> > + *
> > + * @req:	the request.
> > + * @n:		search for the Nth buffer in the req object list  
> 
> It's not very clear to me what "n" is here. Wouldn't it be better to
> pass the queue pointer instead, to get a buffer for a given queue ?

Yep, that would work too and would be much clearer. I'll do that,
thanks for the suggestion.