Recently WARN_ON() calls have been added to warn if the driver is not
properly returning buffers to vb2 in start_streaming (if it fails) or
stop_streaming(). Add comments before those WARN_ON calls that refer
to the videobuf2-core.h header that explains what drivers are supposed
to do in these situations. That should help point developers in the
right direction if they see these warnings.
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
drivers/media/v4l2-core/videobuf2-core.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index c359006..d3f2a22 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1762,6 +1762,12 @@ static int vb2_start_streaming(struct vb2_queue *q)
q->start_streaming_called = 0;
dprintk(1, "driver refused to start streaming\n");
+ /*
+ * If you see this warning, then the driver isn't cleaning up properly
+ * after a failed start_streaming(). See the start_streaming()
+ * documentation in videobuf2-core.h for more information how buffers
+ * should be returned to vb2 in start_streaming().
+ */
if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
unsigned i;
@@ -2123,6 +2129,12 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
if (q->start_streaming_called)
call_void_qop(q, stop_streaming, q);
+ /*
+ * If you see this warning, then the driver isn't cleaning up properly
+ * in stop_streaming(). See the stop_streaming() documentation in
+ * videobuf2-core.h for more information how buffers should be returned
+ * to vb2 in stop_streaming().
+ */
if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
for (i = 0; i < q->num_buffers; ++i)
if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE)
--
2.0.1
--
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