[media] v4l2: add device_caps to struct video_device

Instead of letting drivers fill in device_caps at querycap time,
let them fill it in when the video device is registered.

This has the advantage that in the future the v4l2 core can access
the video device's capabilities and take decisions based on that.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/v4l2-core/v4l2-ioctl.c

@@ -1020,9 +1020,12 @@ static int v4l_querycap(const struct v4l2_ioctl_ops *ops,
 				struct file *file, void *fh, void *arg)
 {
 	struct v4l2_capability *cap = (struct v4l2_capability *)arg;
+	struct video_device *vfd = video_devdata(file);
 	int ret;
 
 	cap->version = LINUX_VERSION_CODE;
+	cap->device_caps = vfd->device_caps;
+	cap->capabilities = vfd->device_caps | V4L2_CAP_DEVICE_CAPS;
 
 	ret = ops->vidioc_querycap(file, fh, cap);
 

include/media/v4l2-dev.h

@@ -92,6 +92,9 @@ struct video_device
 	/* device ops */
 	const struct v4l2_file_operations *fops;
 
+	/* device capabilities as used in v4l2_capabilities */
+	u32 device_caps;
+
 	/* sysfs */
 	struct device dev;		/* v4l device */
 	struct cdev *cdev;		/* character device */