ioctl VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION
&manvol;

# VIDIOC_SUBDEV_G_SELECTION

# VIDIOC_SUBDEV_S_SELECTION

Get or set selection rectangles on a subdev pad

    	int ioctl
    	int fd
    	int request
    	struct v4l2_subdev_selection *argp

## Arguments

`fd`

  &fd;

`request`

  VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION

`argp`

## Description

### Experimental

This is an experimental interface and may change in the future.

The selections are used to configure various image processing functionality performed by the subdevs which affect the image size. This currently includes cropping, scaling and composition.

The selection API replaces the old subdev crop API. All the function of the crop API, and more, are supported by the selections API.

See for more information on how each selection target affects the image processing pipeline inside the subdevice.

### Types of selection targets

There are two types of selection targets: actual and bounds. The ACTUAL targets are the targets which configure the hardware. The BOUNDS target will return a rectangle that contain all possible ACTUAL rectangles.

### Discovering supported features

To discover which targets are supported, the user can perform `VIDIOC_SUBDEV_G_SELECTION` on them. Any unsupported target will return `EINVAL`.

### V4L2 subdev selection targets

&cs-def;
`V4L2_SUBDEV_SEL_TGT_CROP_ACTUAL` | 0x0000 | Actual crop. Defines the cropping performed by the processing step.
`V4L2_SUBDEV_SEL_TGT_CROP_BOUNDS` | 0x0002 | Bounds of the crop rectangle.
`V4L2_SUBDEV_SEL_TGT_COMPOSE_ACTUAL` | 0x0100 | Actual compose rectangle. Used to configure scaling on sink pads and composition on source pads.
`V4L2_SUBDEV_SEL_TGT_COMPOSE_BOUNDS` | 0x0102 | Bounds of the compose rectangle.

### V4L2 subdev selection flags

&cs-def;
`V4L2_SUBDEV_SEL_FLAG_SIZE_GE` | (1 << 0) | Suggest the driver it should choose greater or equal rectangle (in size) than was requested. Albeit the driver may choose a lesser size, it will only do so due to hardware limitations. Without this flag (and `V4L2_SUBDEV_SEL_FLAG_SIZE_LE`) the behaviour is to choose the closest possible rectangle.
`V4L2_SUBDEV_SEL_FLAG_SIZE_LE` | (1 << 1) | Suggest the driver it should choose lesser or equal rectangle (in size) than was requested. Albeit the driver may choose a greater size, it will only do so due to hardware limitations.
`V4L2_SUBDEV_SEL_FLAG_KEEP_CONFIG` | (1 << 2) | The configuration should not be propagated to any further processing steps. If this flag is not given, the configuration is propagated inside the subdevice to all further processing steps.

### struct v4l2_subdev_selection

&cs-str;
__u32 | which | Active or try selection, from &v4l2-subdev-format-whence;.
__u32 | pad | Pad number as reported by the media framework.
__u32 | target | Target selection rectangle. See ..
__u32 | flags | Flags. See .
&v4l2-rect; | rect | Selection rectangle, in pixels.
__u32 | reserved[8] | Reserved for future extensions. Applications and drivers must set the array to zero.

&return-value;

EBUSY

  The selection rectangle can't be changed because the pad is currently busy. This can be caused, for instance, by an active video stream on the pad. The ioctl must not be retried without performing another action to fix the problem first. Only returned by `VIDIOC_SUBDEV_S_SELECTION`

EINVAL

  The &v4l2-subdev-selection; pad references a non-existing pad, the which field references a non-existing format, or the selection target is not supported on the given subdev pad.