[media] vb2: Only requeue buffers immediately once streaming is started

Buffers can be returned back to videobuf2 in driver's streamon handler. In
this case vb2_buffer_done() with buffer state VB2_BUF_STATE_QUEUED will
cause the driver's buf_queue vb2 operation to be called, queueing the same
buffer again only to be returned to videobuf2 using vb2_buffer_done() and so
on.

Add a new buffer state VB2_BUF_STATE_REQUEUEING which, when used as the
state argument to vb2_buffer_done(), will result in buffers queued to the
driver. Using VB2_BUF_STATE_QUEUED will leave the buffer to videobuf2, as it
was before "[media] vb2: allow requeuing buffers while streaming".

Fixes: ce0eff01 ("[media] vb2: allow requeuing buffers while streaming")

[mchehab@osg.samsung.com: fix warning: enumeration value 'VB2_BUF_STATE_REQUEUEING' not handled in switch]
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: stable@vger.kernel.org # for v4.1
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/pci/cobalt/cobalt-irq.c

@@ -139,7 +139,7 @@ static void cobalt_dma_stream_queue_handler(struct cobalt_stream *s)
 	   also know about dropped frames. */
 	cb->vb.v4l2_buf.sequence = s->sequence++;
 	vb2_buffer_done(&cb->vb, (skip || s->unstable_frame) ?
-			VB2_BUF_STATE_QUEUED : VB2_BUF_STATE_DONE);
+			VB2_BUF_STATE_REQUEUEING : VB2_BUF_STATE_DONE);
 }
 
 irqreturn_t cobalt_irq_handler(int irq, void *dev_id)

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

@@ -715,6 +715,7 @@ static void __fill_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b)
 		break;
 	case VB2_BUF_STATE_PREPARING:
 	case VB2_BUF_STATE_DEQUEUED:
+	case VB2_BUF_STATE_REQUEUEING:
 		/* nothing */
 		break;
 	}
@@ -1182,7 +1183,8 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
 
 	if (WARN_ON(state != VB2_BUF_STATE_DONE &&
 		    state != VB2_BUF_STATE_ERROR &&
-		    state != VB2_BUF_STATE_QUEUED))
+		    state != VB2_BUF_STATE_QUEUED &&
+		    state != VB2_BUF_STATE_REQUEUEING))
 		state = VB2_BUF_STATE_ERROR;
 
 #ifdef CONFIG_VIDEO_ADV_DEBUG
@@ -1199,22 +1201,30 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
 	for (plane = 0; plane < vb->num_planes; ++plane)
 		call_void_memop(vb, finish, vb->planes[plane].mem_priv);
 
-	/* Add the buffer to the done buffers list */
 	spin_lock_irqsave(&q->done_lock, flags);
-	vb->state = state;
-	if (state != VB2_BUF_STATE_QUEUED)
+	if (state == VB2_BUF_STATE_QUEUED ||
+	    state == VB2_BUF_STATE_REQUEUEING) {
+		vb->state = VB2_BUF_STATE_QUEUED;
+	} else {
+		/* Add the buffer to the done buffers list */
 		list_add_tail(&vb->done_entry, &q->done_list);
+		vb->state = state;
+	}
 	atomic_dec(&q->owned_by_drv_count);
 	spin_unlock_irqrestore(&q->done_lock, flags);
 
-	if (state == VB2_BUF_STATE_QUEUED) {
+	switch (state) {
+	case VB2_BUF_STATE_QUEUED:
+		return;
+	case VB2_BUF_STATE_REQUEUEING:
 		if (q->start_streaming_called)
 			__enqueue_in_driver(vb);
 		return;
+	default:
+		/* Inform any processes that may be waiting for buffers */
+		wake_up(&q->done_wq);
+		break;
 	}
-
-	/* Inform any processes that may be waiting for buffers */
-	wake_up(&q->done_wq);
 }
 EXPORT_SYMBOL_GPL(vb2_buffer_done);
 

include/media/videobuf2-core.h

@@ -139,6 +139,7 @@ enum vb2_io_modes {
  * @VB2_BUF_STATE_PREPARING:	buffer is being prepared in videobuf
  * @VB2_BUF_STATE_PREPARED:	buffer prepared in videobuf and by the driver
  * @VB2_BUF_STATE_QUEUED:	buffer queued in videobuf, but not in driver
+ * @VB2_BUF_STATE_REQUEUEING:	re-queue a buffer to the driver
  * @VB2_BUF_STATE_ACTIVE:	buffer queued in driver and possibly used
  *				in a hardware operation
  * @VB2_BUF_STATE_DONE:		buffer returned from driver to videobuf, but
@@ -152,6 +153,7 @@ enum vb2_buffer_state {
 	VB2_BUF_STATE_PREPARING,
 	VB2_BUF_STATE_PREPARED,
 	VB2_BUF_STATE_QUEUED,
+	VB2_BUF_STATE_REQUEUEING,
 	VB2_BUF_STATE_ACTIVE,
 	VB2_BUF_STATE_DONE,
 	VB2_BUF_STATE_ERROR,