[media] v4l: Add source change event

This event indicates that the video device has encountered
a source parameter change during runtime. This can typically be a
resolution change detected by a video decoder OR a format change
detected by an input connector.

This needs to be nofified to the userspace and the application may
be expected to reallocate buffers before proceeding. The application
can subscribe to events on a specific pad or input port which
it is interested in.

Signed-off-by: Arun Kumar K <arun.kk@samsung.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/v4l2-event.c b/drivers/media/v4l2-core/v4l2-event.c
index 86dcb54..8761aab 100644
--- a/drivers/media/v4l2-core/v4l2-event.c
+++ b/drivers/media/v4l2-core/v4l2-event.c
@@ -318,3 +318,39 @@ int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
 	return v4l2_event_unsubscribe(fh, sub);
 }
 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
+
+static void v4l2_event_src_replace(struct v4l2_event *old,
+				const struct v4l2_event *new)
+{
+	u32 old_changes = old->u.src_change.changes;
+
+	old->u.src_change = new->u.src_change;
+	old->u.src_change.changes |= old_changes;
+}
+
+static void v4l2_event_src_merge(const struct v4l2_event *old,
+				struct v4l2_event *new)
+{
+	new->u.src_change.changes |= old->u.src_change.changes;
+}
+
+static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
+	.replace = v4l2_event_src_replace,
+	.merge = v4l2_event_src_merge,
+};
+
+int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
+				const struct v4l2_event_subscription *sub)
+{
+	if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
+		return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
+
+int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
+		struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
+{
+	return v4l2_src_change_event_subscribe(fh, sub);
+}
+EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);