[PATCH 3/4] media: qcom: camss: always stop the pipeline in stop_streaming

[Allan Siriani]

video_stop_streaming() walks the pipeline upstream and calls
.s_stream(0) on every subdev. It gives up on the first non-zero return,
without stopping the media pipeline and without returning the queued
buffers to vb2.

A subdev without .s_stream() returns -ENOIOCTLCMD. video_start_streaming()
already ignores that, but video_stop_streaming() does not, so with such a
subdev in the pipeline, e.g. the pixel array entity of the MT9M114 sensor
driver, every stream off:

- triggers the vb2 WARN about buffers still owned by the driver,
- leaves the pipeline started, so the next VIDIOC_STREAMON and
  "media-ctl -r" fail with -EBUSY.

Treat -ENOIOCTLCMD as success, as at stream on, and only log real
errors, then always stop the pipeline and flush the buffers: a
.stop_streaming() callback cannot fail and must give back all buffers.

Signed-off-by: Allan Siriani <allan@xxxxxxxxxxxxxxxxxxx>
---
 drivers/media/platform/qcom/camss/camss-video.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/media/platform/qcom/camss/camss-video.c b/drivers/media/platform/qcom/camss/camss-video.c
index 2c15546c8..9091eaa18 100644
--- a/drivers/media/platform/qcom/camss/camss-video.c
+++ b/drivers/media/platform/qcom/camss/camss-video.c
@@ -361,12 +361,16 @@ static void video_stop_streaming(struct vb2_queue *q)
 		entity = pad->entity;
 		subdev = media_entity_to_v4l2_subdev(entity);
 
+		/*
+		 * Subdevs without .s_stream(), such as a sensor pixel array
+		 * entity, return -ENOIOCTLCMD, as at stream on. On a real error
+		 * keep going: the pipeline must be stopped and the buffers
+		 * returned to vb2 in any case.
+		 */
 		ret = v4l2_subdev_call(subdev, video, s_stream, 0);
-
-		if (ret) {
-			dev_err(video->camss->dev, "Video pipeline stop failed: %d\n", ret);
-			return;
-		}
+		if (ret && ret != -ENOIOCTLCMD)
+			dev_err(video->camss->dev,
+				"Failed to stop %s: %d\n", entity->name, ret);
 	}
 
 	video_device_pipeline_stop(vdev);
-- 
2.43.0