[media] vb2: Don't WARN when v4l2_buffer.bytesused is 0 for multiplanar buffers

Commit f61bf13b ("[media] vb2: add allow_zero_bytesused flag to the
vb2_queue struct") added a WARN_ONCE to catch usage of a deprecated API
using a zero value for v4l2_buffer.bytesused.

However, the condition is checked incorrectly, as the v4L2_buffer
bytesused field is supposed to be ignored for multiplanar buffers. This
results in spurious warnings when using the multiplanar API.

Fix it by checking v4l2_buffer.bytesused for uniplanar buffers and
v4l2_plane.bytesused for multiplanar buffers.

Fixes: f61bf13b ("[media] vb2: add allow_zero_bytesused flag to the vb2_queue struct")
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Cc: stable@vger.kernel.org # for v4.0
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

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

@@ -1242,6 +1242,23 @@ void vb2_discard_done(struct vb2_queue *q)
 }
 EXPORT_SYMBOL_GPL(vb2_discard_done);
 
+static void vb2_warn_zero_bytesused(struct vb2_buffer *vb)
+{
+	static bool __check_once __read_mostly;
+
+	if (__check_once)
+		return;
+
+	__check_once = true;
+	__WARN();
+
+	pr_warn_once("use of bytesused == 0 is deprecated and will be removed in the future,\n");
+	if (vb->vb2_queue->allow_zero_bytesused)
+		pr_warn_once("use VIDIOC_DECODER_CMD(V4L2_DEC_CMD_STOP) instead.\n");
+	else
+		pr_warn_once("use the actual size instead.\n");
+}
+
 /**
  * __fill_vb2_buffer() - fill a vb2_buffer with information provided in a
  * v4l2_buffer by the userspace. The caller has already verified that struct
@@ -1252,16 +1269,6 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
 {
 	unsigned int plane;
 
-	if (V4L2_TYPE_IS_OUTPUT(b->type)) {
-		if (WARN_ON_ONCE(b->bytesused == 0)) {
-			pr_warn_once("use of bytesused == 0 is deprecated and will be removed in the future,\n");
-			if (vb->vb2_queue->allow_zero_bytesused)
-				pr_warn_once("use VIDIOC_DECODER_CMD(V4L2_DEC_CMD_STOP) instead.\n");
-			else
-				pr_warn_once("use the actual size instead.\n");
-		}
-	}
-
 	if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
 		if (b->memory == V4L2_MEMORY_USERPTR) {
 			for (plane = 0; plane < vb->num_planes; ++plane) {
@@ -1302,6 +1309,9 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
 				struct v4l2_plane *pdst = &v4l2_planes[plane];
 				struct v4l2_plane *psrc = &b->m.planes[plane];
 
+				if (psrc->bytesused == 0)
+					vb2_warn_zero_bytesused(vb);
+
 				if (vb->vb2_queue->allow_zero_bytesused)
 					pdst->bytesused = psrc->bytesused;
 				else
@@ -1336,6 +1346,9 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
 		}
 
 		if (V4L2_TYPE_IS_OUTPUT(b->type)) {
+			if (b->bytesused == 0)
+				vb2_warn_zero_bytesused(vb);
+
 			if (vb->vb2_queue->allow_zero_bytesused)
 				v4l2_planes[0].bytesused = b->bytesused;
 			else