media/drivers/uvcvideo.rst

28 control enumeration.
37 Control mappings
41 control mappings at runtime. These allow for individual XU controls or byte
45 triggers a read or write of the associated XU control.
47 The ioctl used to create these control mappings is called UVCIOC_CTRL_MAP.
49 beforehand (UVCIOC_CTRL_ADD) to pass XU control information to the UVC driver.
57 3. Driver specific XU control interface
65 directly map to the low-level UVC control requests.
67 In order to make such a request the UVC unit ID of the control's extension unit
68 and the control selector need to be known. This information either needs to be
73 Unless the control size is already known it is necessary to first make a
76 UVC_GET_CUR or UVC_SET_CUR are valid requests for a given control, a
92 The API doesn't currently provide a fine-grained access control facility. The
109 UVCIOC_CTRL_MAP - Map a UVC control to a V4L2 control
116 	This ioctl creates a mapping between a UVC control or part of a UVC
117 	control and a V4L2 control. Once mappings are defined, userspace
118 	applications can access vendor-defined UVC control through the V4L2
119 	control API.
122 	structure with information about an existing UVC control defined with
123 	UVCIOC_CTRL_ADD and a new V4L2 control.
125 	A UVC control can be mapped to several V4L2 controls. For instance,
126 	a UVC pan/tilt control could be mapped to separate pan and tilt V4L2
127 	controls. The UVC control is divided into non overlapping fields using
129 	V4L2 control.
144 		No such UVC control.
146 		The requested offset and size would overflow the UVC control.
156 	__u32	id		V4L2 control identifier
157 	__u8	name[32]	V4L2 control name
159 	__u8	selector	UVC control selector
160 	__u8	size		V4L2 control size (in bits)
161 	__u8	offset		V4L2 control offset (in bits)
163 		v4l2_type	V4L2 control type
165 		data_type	UVC control data type
178 	UVC_CTRL_DATA_TYPE_RAW		Raw control (byte array)
187 UVCIOC_CTRL_QUERY - Query a UVC XU control
193 	This ioctl queries a UVC XU control identified by its extension unit ID
194 	and control selector.
197 	correspond to the low-level control requests described in the UVC
201 		Obtain the current value of the control.
203 		Obtain the minimum value of the control.
205 		Obtain the maximum value of the control.
207 		Obtain the default value of the control.
209 		Query the resolution of the control, i.e. the step size of the
210 		allowed control values.
212 		Query the size of the control in bytes.
214 		Query the control information bitmap, which indicates whether
217 		Update the value of the control.
220 	control. Exceptions are the UVC_GET_LEN and UVC_GET_INFO queries, for
237 		The device does not support the given control or the specified
244 		The given request is not supported by the given control.
255 	__u8	selector	Control selector
257 	__u16	size		Control data size (in bytes)
258 	__u8	*data		Control value
267 	This control determines the region of interest (ROI). ROI is a
277 	The value of ``V4L2_CID_REGION_OF_INTEREST_AUTO`` control determines
280 	An example of use of this control, can be found in the: