[RFC v4 02/18] vb2: Move buffer cache synchronisation to prepare from queue

[Sakari Ailus]

The buffer cache should be synchronised in buffer preparation, not when
the buffer is queued to the device. Fix this.

Mmap buffers do not need cache synchronisation since they are always
coherent.

Signed-off-by: Sakari Ailus <sakari.ailus at linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil at cisco.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 8df680d..8bf3369 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1227,23 +1227,19 @@ static int __prepare_dmabuf(struct vb2_buffer *vb, const void *pb)
 static void __enqueue_in_driver(struct vb2_buffer *vb)
 {
 	struct vb2_queue *q = vb->vb2_queue;
-	unsigned int plane;
 
 	vb->state = VB2_BUF_STATE_ACTIVE;
 	atomic_inc(&q->owned_by_drv_count);
 
 	trace_vb2_buf_queue(q, vb);
 
-	/* sync buffers */
-	for (plane = 0; plane < vb->num_planes; ++plane)
-		call_void_memop(vb, prepare, vb->planes[plane].mem_priv);
-
 	call_void_vb_qop(vb, buf_queue, vb);
 }
 
 static int __buf_prepare(struct vb2_buffer *vb, const void *pb)
 {
 	struct vb2_queue *q = vb->vb2_queue;
+	unsigned int plane;
 	int ret;
 
 	if (q->error) {
@@ -1268,11 +1264,19 @@ static int __buf_prepare(struct vb2_buffer *vb, const void *pb)
 		ret = -EINVAL;
 	}
 
-	if (ret)
+	if (ret) {
 		dprintk(1, "buffer preparation failed: %d\n", ret);
-	vb->state = ret ? VB2_BUF_STATE_DEQUEUED : VB2_BUF_STATE_PREPARED;
+		vb->state = VB2_BUF_STATE_DEQUEUED;
+		return ret;
+	}
 
-	return ret;
+	/* sync buffers */
+	for (plane = 0; plane < vb->num_planes; ++plane)
+		call_void_memop(vb, prepare, vb->planes[plane].mem_priv);
+
+	vb->state = VB2_BUF_STATE_PREPARED;
+
+	return 0;
 }
 
 int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb)
-- 
2.7.4