media: ov2680: Fix exposure and gain ctrls range and default value

The exposure control's max effective value is VTS - 8, set the control
range to match this. Thas means that if/when a future commit makes VTS
configurable as a control itself the exposure range needs to be
updated dynamically to match the VTS value.

The gain control goes from 0 - 1023, higher values wrap around to
the lowest gain setting.

The gain control, controls an analog gain so use V4L2_CID_ANALOGUE_GAIN
for it instead of V4L2_CID_GAIN.

Also stop setting 0 as default for both controls this leads to
a totally black picture which is no good. This is esp. important
for tests of the sensor driver without (userspace driven)
auto exposure / gain.
Acked-by: Rui Miguel Silva <rmfrfs@gmail.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/i2c/ov2680.c

@@ -81,6 +81,9 @@
 /* If possible send 16 extra rows / lines to the ISP as padding */
 #define OV2680_END_MARGIN			16
 
+/* Max exposure time is VTS - 8 */
+#define OV2680_INTEGRATION_TIME_MARGIN		8
+
 #define OV2680_DEFAULT_WIDTH			800
 #define OV2680_DEFAULT_HEIGHT			600
 
@@ -779,7 +782,7 @@ static int ov2680_s_ctrl(struct v4l2_ctrl *ctrl)
 	}
 
 	switch (ctrl->id) {
-	case V4L2_CID_GAIN:
+	case V4L2_CID_ANALOGUE_GAIN:
 		ret = ov2680_gain_set(sensor, ctrl->val);
 		break;
 	case V4L2_CID_EXPOSURE:
@@ -849,6 +852,7 @@ static int ov2680_v4l2_register(struct ov2680_dev *sensor)
 	const struct v4l2_ctrl_ops *ops = &ov2680_ctrl_ops;
 	struct ov2680_ctrls *ctrls = &sensor->ctrls;
 	struct v4l2_ctrl_handler *hdl = &ctrls->handler;
+	int exp_max = OV2680_LINES_PER_FRAME - OV2680_INTEGRATION_TIME_MARGIN;
 	int ret = 0;
 
 	v4l2_i2c_subdev_init(&sensor->sd, client, &ov2680_subdev_ops);
@@ -874,9 +878,10 @@ static int ov2680_v4l2_register(struct ov2680_dev *sensor)
 					0, 0, test_pattern_menu);
 
 	ctrls->exposure = v4l2_ctrl_new_std(hdl, ops, V4L2_CID_EXPOSURE,
-					    0, 32767, 1, 0);
+					    0, exp_max, 1, exp_max);
 
-	ctrls->gain = v4l2_ctrl_new_std(hdl, ops, V4L2_CID_GAIN, 0, 2047, 1, 0);
+	ctrls->gain = v4l2_ctrl_new_std(hdl, ops, V4L2_CID_ANALOGUE_GAIN,
+					0, 1023, 1, 250);
 
 	if (hdl->error) {
 		ret = hdl->error;