[RESEND PATCH v2 1/4] media: vb2: Add a helper to get the vb2 buffer attached to a request

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

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 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 640aabe69450..d363476712dd 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.
+ * @n:		search for the Nth buffer in the req object list
+ *
+ * Return a vb2 buffer or NULL if there's no buffer at the specified position
+ */
+struct vb2_buffer *vb2_request_get_buf(struct media_request *req,
+				       unsigned int n);
+
 #endif /* _MEDIA_VIDEOBUF2_CORE_H */
-- 
2.21.0