media: add V4L2_CID_UNIT_CELL_SIZE control

This control returns the unit cell size in nanometres. The struct provides
the width and the height in separated fields to take into consideration
asymmetric pixels and/or hardware binning.
This control is required for automatic calibration of sensors/cameras.
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Ricardo Ribalda Delgado <ribalda@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/v4l2-core/v4l2-ctrls.c

@@ -996,6 +996,7 @@ const char *v4l2_ctrl_get_name(u32 id)
 	case V4L2_CID_AUTO_FOCUS_RANGE:		return "Auto Focus, Range";
 	case V4L2_CID_PAN_SPEED:		return "Pan, Speed";
 	case V4L2_CID_TILT_SPEED:		return "Tilt, Speed";
+	case V4L2_CID_UNIT_CELL_SIZE:		return "Unit Cell Size";
 
 	/* FM Radio Modulator controls */
 	/* Keep the order of the 'case's the same as in v4l2-controls.h! */
@@ -1377,6 +1378,10 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
 	case V4L2_CID_MPEG_VIDEO_VP8_FRAME_HEADER:
 		*type = V4L2_CTRL_TYPE_VP8_FRAME_HEADER;
 		break;
+	case V4L2_CID_UNIT_CELL_SIZE:
+		*type = V4L2_CTRL_TYPE_AREA;
+		*flags |= V4L2_CTRL_FLAG_READ_ONLY;
+		break;
 	default:
 		*type = V4L2_CTRL_TYPE_INTEGER;
 		break;

include/uapi/linux/v4l2-controls.h

@@ -1034,6 +1034,7 @@ enum v4l2_jpeg_chroma_subsampling {
 #define V4L2_CID_TEST_PATTERN_GREENR		(V4L2_CID_IMAGE_SOURCE_CLASS_BASE + 5)
 #define V4L2_CID_TEST_PATTERN_BLUE		(V4L2_CID_IMAGE_SOURCE_CLASS_BASE + 6)
 #define V4L2_CID_TEST_PATTERN_GREENB		(V4L2_CID_IMAGE_SOURCE_CLASS_BASE + 7)
+#define V4L2_CID_UNIT_CELL_SIZE			(V4L2_CID_IMAGE_SOURCE_CLASS_BASE + 8)
 
 
 /* Image processing controls */