media: vb2: vb2_find_timestamp: drop restriction on buffer state

There really is no reason why vb2_find_timestamp can't just find
buffers in any state. Drop that part of the test.

This also means that vb->timestamp should only be set to 0 when
the driver doesn't copy timestamps.

This change allows for more efficient pipelining (i.e. you can use
a buffer for a reference frame even when it is queued).
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

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

@@ -567,7 +567,7 @@ static int __fill_vb2_buffer(struct vb2_buffer *vb, struct vb2_plane *planes)
 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
 	unsigned int plane;
 
-	if (!vb->vb2_queue->is_output || !vb->vb2_queue->copy_timestamp)
+	if (!vb->vb2_queue->copy_timestamp)
 		vb->timestamp = 0;
 
 	for (plane = 0; plane < vb->num_planes; ++plane) {
@@ -594,14 +594,9 @@ int vb2_find_timestamp(const struct vb2_queue *q, u64 timestamp,
 {
 	unsigned int i;
 
-	for (i = start_idx; i < q->num_buffers; i++) {
-		struct vb2_buffer *vb = q->bufs[i];
-
-		if ((vb->state == VB2_BUF_STATE_DEQUEUED ||
-		     vb->state == VB2_BUF_STATE_DONE) &&
-		    vb->timestamp == timestamp)
+	for (i = start_idx; i < q->num_buffers; i++)
+		if (q->bufs[i]->timestamp == timestamp)
 			return i;
-	}
 	return -1;
 }
 EXPORT_SYMBOL_GPL(vb2_find_timestamp);

include/media/videobuf2-v4l2.h

@@ -59,8 +59,7 @@ struct vb2_v4l2_buffer {
  * vb2_find_timestamp() - Find buffer with given timestamp in the queue
  *
  * @q:		pointer to &struct vb2_queue with videobuf2 queue.
- * @timestamp:	the timestamp to find. Only buffers in state DEQUEUED or DONE
- *		are considered.
+ * @timestamp:	the timestamp to find.
  * @start_idx:	the start index (usually 0) in the buffer array to start
  *		searching from. Note that there may be multiple buffers
  *		with the same timestamp value, so you can restart the search