Re: [RFC PATCH 1/5] media: vb2: Add a helper to get the vb2 buffer attached to a request

[Boris Brezillon <boris.brezillon@collabora.com>]

On Mon, 5 Aug 2019 10:12:53 -0300
Hans Verkuil <hverkuil@xs4all.nl> wrote:

> On 8/5/19 6:48 AM, Boris Brezillon wrote:
> > vb2_request_get_buf() returns the N-th buffer attached to a media
> > request.
> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> > ---
> >   .../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..58769f0c8665 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 idx)
> > +{
> > +	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++ < idx)
> > +			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 640aabe69450..febf3261a120 100644
> > --- a/include/media/videobuf2-core.h
> > +++ b/include/media/videobuf2-core.h
> > @@ -1222,4 +1222,15 @@ 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.
> > + * @idx:	index of the buffer in the req object list  
> 
> This is confusing: it suggests that you are talking about the buffer
> index itself (buf->index) instead of the nth buffer in the request.

How about:

@n: search for the Nth buffer in the req object list

> 
> Looks good otherwise.
> 
> Regards,
> 
> 	Hans
> 
> > + *
> > + * Return a vb2 buffer or NULL if there's no buffer at the specified index
> > + */
> > +struct vb2_buffer *vb2_request_get_buf(struct media_request *req,
> > +				       unsigned int idx);
> > +
> >   #endif /* _MEDIA_VIDEOBUF2_CORE_H */
> >   
>