staging: bcm2835-camera: Ensure all buffers are returned on disable

With the recent change to match MMAL and V4L2 buffers there
is a need to wait for all MMAL buffers to be returned during
stop_streaming.

Fixes: 93841670 ("staging: bcm2835-camera: Remove V4L2/MMAL buffer remapping")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c

@@ -584,6 +584,7 @@ static void stop_streaming(struct vb2_queue *vq)
 	int ret;
 	unsigned long timeout;
 	struct bm2835_mmal_dev *dev = vb2_get_drv_priv(vq);
+	struct vchiq_mmal_port *port = dev->capture.port;
 
 	v4l2_dbg(1, bcm2835_v4l2_debug, &dev->v4l2_dev, "%s: dev:%p\n",
 		 __func__, dev);
@@ -607,12 +608,6 @@ static void stop_streaming(struct vb2_queue *vq)
 				      &dev->capture.frame_count,
 				      sizeof(dev->capture.frame_count));
 
-	/* wait for last frame to complete */
-	timeout = wait_for_completion_timeout(&dev->capture.frame_cmplt, HZ);
-	if (timeout == 0)
-		v4l2_err(&dev->v4l2_dev,
-			 "timed out waiting for frame completion\n");
-
 	v4l2_dbg(1, bcm2835_v4l2_debug, &dev->v4l2_dev,
 		 "disabling connection\n");
 
@@ -627,6 +622,21 @@ static void stop_streaming(struct vb2_queue *vq)
 			 ret);
 	}
 
+	/* wait for all buffers to be returned */
+	while (atomic_read(&port->buffers_with_vpu)) {
+		v4l2_dbg(1, bcm2835_v4l2_debug, &dev->v4l2_dev,
+			 "%s: Waiting for buffers to be returned - %d outstanding\n",
+			 __func__, atomic_read(&port->buffers_with_vpu));
+		timeout = wait_for_completion_timeout(&dev->capture.frame_cmplt,
+						      HZ);
+		if (timeout == 0) {
+			v4l2_err(&dev->v4l2_dev, "%s: Timeout waiting for buffers to be returned - %d outstanding\n",
+				 __func__,
+				 atomic_read(&port->buffers_with_vpu));
+			break;
+		}
+	}
+
 	if (disable_camera(dev) < 0)
 		v4l2_err(&dev->v4l2_dev, "Failed to disable camera\n");
 }

drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c

@@ -246,6 +246,8 @@ static void buffer_work_cb(struct work_struct *work)
 	struct mmal_msg_context *msg_context =
 		container_of(work, struct mmal_msg_context, u.bulk.work);
 
+	atomic_dec(&msg_context->u.bulk.port->buffers_with_vpu);
+
 	msg_context->u.bulk.port->buffer_cb(msg_context->u.bulk.instance,
 					    msg_context->u.bulk.port,
 					    msg_context->u.bulk.status,
@@ -389,6 +391,8 @@ buffer_from_host(struct vchiq_mmal_instance *instance,
 	INIT_WORK(&msg_context->u.bulk.buffer_to_host_work,
 		  buffer_to_host_work_cb);
 
+	atomic_inc(&port->buffers_with_vpu);
+
 	/* prep the buffer from host message */
 	memset(&m, 0xbc, sizeof(m));	/* just to make debug clearer */
 

drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.h

@@ -72,6 +72,9 @@ struct vchiq_mmal_port {
 	struct list_head buffers;
 	/* lock to serialise adding and removing buffers from list */
 	spinlock_t slock;
+
+	/* Count of buffers the VPU has yet to return */
+	atomic_t buffers_with_vpu;
 	/* callback on buffer completion */
 	vchiq_mmal_buffer_cb buffer_cb;
 	/* callback context */