Name

VIDIOC_SUBDEV_G_SELECTION, VIDIOC_SUBDEV_S_SELECTION — Get or set selection rectangles on a subdev pad

Synopsis

int ioctl(int fd,
 int request,
 struct v4l2_subdev_selection *argp);
 

Arguments

fd

File descriptor returned by open().

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 the section called “Sub-device Interface” 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.

Selection targets and flags are documented in the section called “Common selection definitions”.

Table A.108. struct v4l2_subdev_selection

__u32whichActive or try selection, from enum v4l2_subdev_format_whence.
__u32padPad number as reported by the media framework.
__u32targetTarget selection rectangle. See the section called “Common selection definitions”.
__u32flagsFlags. See the section called “Selection flags”.
struct v4l2_rectrSelection rectangle, in pixels.
__u32reserved[8]Reserved for future extensions. Applications and drivers must set the array to zero.

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.

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 struct 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.