7.61. ioctl VIDIOC_SUBDEV_G_ROUTING, VIDIOC_SUBDEV_S_ROUTING¶
7.61.1. Name¶
VIDIOC_SUBDEV_G_ROUTING - VIDIOC_SUBDEV_S_ROUTING - Get or set routing between streams of media pads in a media entity.
7.61.2. Synopsis¶
- 
VIDIOC_SUBDEV_G_ROUTING¶
int ioctl(int fd, VIDIOC_SUBDEV_G_ROUTING, struct v4l2_subdev_routing *argp)
- 
VIDIOC_SUBDEV_S_ROUTING¶
int ioctl(int fd, VIDIOC_SUBDEV_S_ROUTING, struct v4l2_subdev_routing *argp)
7.61.3. Arguments¶
- fd
- File descriptor returned by open(). 
- argp
- Pointer to struct - v4l2_subdev_routing.
7.61.4. Description¶
These ioctls are used to get and set the routing in a media entity. The routing configuration determines the flows of data inside an entity.
Drivers report their current routing tables using the
VIDIOC_SUBDEV_G_ROUTING ioctl and application may enable or disable routes
with the VIDIOC_SUBDEV_S_ROUTING ioctl, by adding or removing routes and
setting or clearing flags of the  flags field of a
struct v4l2_subdev_route.
All stream configurations are reset when VIDIOC_SUBDEV_S_ROUTING is called. This
means that the userspace must reconfigure all streams after calling the ioctl
with e.g. VIDIOC_SUBDEV_S_FMT.
Only subdevices which have both sink and source pads can support routing.
When inspecting routes through VIDIOC_SUBDEV_G_ROUTING and the application
provided num_routes is not big enough to contain all the available routes
the subdevice exposes, drivers return the ENOSPC error code and adjust the
value of the num_routes field. Application should then reserve enough memory
for all the route entries and call VIDIOC_SUBDEV_G_ROUTING again.
On a successful VIDIOC_SUBDEV_G_ROUTING call the driver updates the
num_routes field to reflect the actual number of routes returned.
- 
type v4l2_subdev_routing¶
| __u32 | 
 | Format to modified, from enum v4l2_subdev_format_whence. | 
| struct  | 
 | Array of struct  | 
| __u32 | 
 | Number of entries of the routes array | 
| __u32 | 
 | Reserved for future extensions. Applications and drivers must set the array to zero. | 
- 
type v4l2_subdev_route¶
| __u32 | 
 | Sink pad number. | 
| __u32 | 
 | Sink pad stream number. | 
| __u32 | 
 | Source pad number. | 
| __u32 | 
 | Source pad stream number. | 
| __u32 | 
 | Route enable/disable flags v4l2_subdev_routing_flags. | 
| __u32 | 
 | Reserved for future extensions. Applications and drivers must set the array to zero. | 
| V4L2_SUBDEV_ROUTE_FL_ACTIVE | 0x0001 | The route is enabled. Set by applications. | 
7.61.5. Return Value¶
On success 0 is returned, on error -1 and the errno variable is set
appropriately. The generic error codes are described at the
Generic Error Codes chapter.
- ENOSPC
- The application provided - num_routesis not big enough to contain all the available routes the subdevice exposes.
- EINVAL
- The sink or source pad identifiers reference a non-existing pad, or reference pads of different types (ie. the sink_pad identifiers refers to a source pad). 
- E2BIG
- The application provided - num_routesfor- VIDIOC_SUBDEV_S_ROUTINGis larger than the number of routes the driver can handle.