3 files changed, 67 insertions, 1 deletions

diff --git a/drivers/media/video/v4l2-fh.c b/drivers/media/video/v4l2-fh.c
index aab2fb639ef1..d78f184f40c5 100644
--- a/drivers/media/video/v4l2-fh.c
+++ b/drivers/media/video/v4l2-fh.c
@@ -34,7 +34,16 @@ int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
 	INIT_LIST_HEAD(&fh->list);
 	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
 
-	return v4l2_event_init(fh);
+	/*
+	 * fh->events only needs to be initialized if the driver
+	 * supports the VIDIOC_SUBSCRIBE_EVENT ioctl.
+	 */
+	if (vdev->ioctl_ops && vdev->ioctl_ops->vidioc_subscribe_event)
+		return v4l2_event_init(fh);
+
+	fh->events = NULL;
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_fh_init);
 
diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index 2ceaa152a450..0eeceae50329 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -26,6 +26,8 @@
 #endif
 #include <media/v4l2-common.h>
 #include <media/v4l2-ioctl.h>
+#include <media/v4l2-fh.h>
+#include <media/v4l2-event.h>
 #include <media/v4l2-chip-ident.h>
 
 #define dbgarg(cmd, fmt, arg...) \
@@ -1951,7 +1953,55 @@ static long __video_do_ioctl(struct file *file,
 		}
 		break;
 	}
+	case VIDIOC_DQEVENT:
+	{
+		struct v4l2_event *ev = arg;
+
+		if (!ops->vidioc_subscribe_event)
+			break;
+
+		ret = v4l2_event_dequeue(fh, ev, file->f_flags & O_NONBLOCK);
+		if (ret < 0) {
+			dbgarg(cmd, "no pending events?");
+			break;
+		}
+		dbgarg(cmd,
+		       "pending=%d, type=0x%8.8x, sequence=%d, "
+		       "timestamp=%lu.%9.9lu ",
+		       ev->pending, ev->type, ev->sequence,
+		       ev->timestamp.tv_sec, ev->timestamp.tv_nsec);
+		break;
+	}
+	case VIDIOC_SUBSCRIBE_EVENT:
+	{
+		struct v4l2_event_subscription *sub = arg;
 
+		if (!ops->vidioc_subscribe_event)
+			break;
+
+		ret = ops->vidioc_subscribe_event(fh, sub);
+		if (ret < 0) {
+			dbgarg(cmd, "failed, ret=%ld", ret);
+			break;
+		}
+		dbgarg(cmd, "type=0x%8.8x", sub->type);
+		break;
+	}
+	case VIDIOC_UNSUBSCRIBE_EVENT:
+	{
+		struct v4l2_event_subscription *sub = arg;
+
+		if (!ops->vidioc_unsubscribe_event)
+			break;
+
+		ret = ops->vidioc_unsubscribe_event(fh, sub);
+		if (ret < 0) {
+			dbgarg(cmd, "failed, ret=%ld", ret);
+			break;
+		}
+		dbgarg(cmd, "type=0x%8.8x", sub->type);
+		break;
+	}
 	default:
 	{
 		if (!ops->vidioc_default)
diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
index e8ba0f2efbae..06daa6e8e051 100644
--- a/include/media/v4l2-ioctl.h
+++ b/include/media/v4l2-ioctl.h
@@ -21,6 +21,8 @@
 #include <linux/videodev2.h>
 #endif
 
+struct v4l2_fh;
+
 struct v4l2_ioctl_ops {
 	/* ioctl callbacks */
 
@@ -254,6 +256,11 @@ struct v4l2_ioctl_ops {
 	int (*vidioc_g_dv_timings) (struct file *file, void *fh,
 				    struct v4l2_dv_timings *timings);
 
+	int (*vidioc_subscribe_event)  (struct v4l2_fh *fh,
+					struct v4l2_event_subscription *sub);
+	int (*vidioc_unsubscribe_event)(struct v4l2_fh *fh,
+					struct v4l2_event_subscription *sub);
+
 	/* For other private ioctls */
 	long (*vidioc_default)	       (struct file *file, void *fh,
 					int cmd, void *arg);