[media] vb2: regression fix: always set length field.

Commit dc77523c ensured that m.offset is
only set for the MMAP memory mode by calling __setup_offsets only for that
mode.

However, __setup_offsets also initializes the length fields, and that should
be done regardless of the memory mode. Because of that change the v4l2-ctl
test application fails for the USERPTR mode.

This fix creates a __setup_lengths function that sets the length, and
__setup_offsets just sets the offset and no longer touches the length.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>

drivers/media/v4l2-core/videobuf2-core.c

@@ -144,6 +144,25 @@ static void __vb2_buf_dmabuf_put(struct vb2_buffer *vb)
 		__vb2_plane_dmabuf_put(q, &vb->planes[plane]);
 }
 
+/**
+ * __setup_lengths() - setup initial lengths for every plane in
+ * every buffer on the queue
+ */
+static void __setup_lengths(struct vb2_queue *q, unsigned int n)
+{
+	unsigned int buffer, plane;
+	struct vb2_buffer *vb;
+
+	for (buffer = q->num_buffers; buffer < q->num_buffers + n; ++buffer) {
+		vb = q->bufs[buffer];
+		if (!vb)
+			continue;
+
+		for (plane = 0; plane < vb->num_planes; ++plane)
+			vb->v4l2_planes[plane].length = q->plane_sizes[plane];
+	}
+}
+
 /**
  * __setup_offsets() - setup unique offsets ("cookies") for every plane in
  * every buffer on the queue
@@ -169,7 +188,6 @@ static void __setup_offsets(struct vb2_queue *q, unsigned int n)
 			continue;
 
 		for (plane = 0; plane < vb->num_planes; ++plane) {
-			vb->v4l2_planes[plane].length = q->plane_sizes[plane];
 			vb->v4l2_planes[plane].m.mem_offset = off;
 
 			dprintk(3, "Buffer %d, plane %d offset 0x%08lx\n",
@@ -241,6 +259,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum v4l2_memory memory,
 		q->bufs[q->num_buffers + buffer] = vb;
 	}
 
+	__setup_lengths(q, buffer);
 	if (memory == V4L2_MEMORY_MMAP)
 		__setup_offsets(q, buffer);