ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS &manvol; VIDIOC_G_EXT_CTRLS VIDIOC_S_EXT_CTRLS VIDIOC_TRY_EXT_CTRLS Get or set the value of several controls, try control values int ioctl int fd int request struct v4l2_ext_controls *argp fd &fd; request VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS argp These ioctls allow the caller to get or set multiple controls atomically. Control IDs are grouped into control classes (see ) and all controls in the control array must belong to the same control class. Applications must always fill in the count, ctrl_class, controls and reserved fields of &v4l2-ext-controls;, and initialize the &v4l2-ext-control; array pointed to by the controls fields. To get the current value of a set of controls applications initialize the id field of each &v4l2-ext-control; and call the VIDIOC_G_EXT_CTRLS ioctl. To change the value of a set of controls applications initialize the id and value fields of a &v4l2-ext-control; and call the VIDIOC_S_EXT_CTRLS ioctl. The controls will only be set if all control values are valid. To check if the a set of controls have correct values applications initialize the id and value fields of a &v4l2-ext-control; and call the VIDIOC_TRY_EXT_CTRLS ioctl. It is up to the driver whether wrong values are automatically adjusted to a valid value or if an error is returned. When the id or ctrl_class is invalid drivers return an &EINVAL;. When the value is out of bounds drivers can choose to take the closest valid value or return an &ERANGE;, whatever seems more appropriate. In the first case the new value is set in &v4l2-ext-control;. The driver will only set/get these controls if all control values are correct. This prevents the situation where only some of the controls were set/get. Only low-level errors (⪚ a failed i2c command) can still cause this situation. &cs-ustr; __u32 id Identifies the control, set by the application. __u32 reserved2[2] Reserved for future extensions. Drivers and applications must set the array to zero. union (anonymous) __s32 value New value or current value. __s64 value64 New value or current value. void * reserved Reserved for future pointer-type controls. Currently unused. &cs-str; __u32 ctrl_class The control class to which all controls belong, see . __u32 count The number of controls in the controls array. May also be zero. __u32 error_idx Set by the driver in case of an error. It is the index of the control causing the error or equal to 'count' when the error is not associated with a particular control. Undefined when the ioctl returns 0 (success). __u32 reserved[2] Reserved for future extensions. Drivers and applications must set the array to zero. &v4l2-ext-control; * controls Pointer to an array of count v4l2_ext_control structures. Ignored if count equals zero. &cs-def; V4L2_CTRL_CLASS_USER 0x980000 The class containing user controls. These controls are described in . All controls that can be set using the &VIDIOC-S-CTRL; and &VIDIOC-G-CTRL; ioctl belong to this class. V4L2_CTRL_CLASS_MPEG 0x990000 The class containing MPEG compression controls. These controls are described in section . &return-value; EINVAL The &v4l2-ext-control; id is invalid or the &v4l2-ext-controls; ctrl_class is invalid. This error code is also returned by the VIDIOC_S_EXT_CTRLS and VIDIOC_TRY_EXT_CTRLS ioctls if two or more control values are in conflict. ERANGE The &v4l2-ext-control; value is out of bounds. EBUSY The control is temporarily not changeable, possibly because another applications took over control of the device function this control belongs to.