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);