media: ov5675: correct the maximum exposure value

The unit of exposure value is different from other OmniVision sensors,
driver will divide by 2 before set register, the exposure range exposed
by v4l2 ctrl to user should be same as others, so the calculation for
the maximum exposure value in current driver need be fixed.
Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/i2c/ov5675.c

@@ -666,8 +666,8 @@ static int ov5675_set_ctrl(struct v4l2_ctrl *ctrl)
 	/* Propagate change of current control to all related controls */
 	if (ctrl->id == V4L2_CID_VBLANK) {
 		/* Update max exposure while meeting expected vblanking */
-		exposure_max = (ov5675->cur_mode->height + ctrl->val -
-			       OV5675_EXPOSURE_MAX_MARGIN) / 2;
+		exposure_max = ov5675->cur_mode->height + ctrl->val -
+			OV5675_EXPOSURE_MAX_MARGIN;
 		__v4l2_ctrl_modify_range(ov5675->exposure,
 					 ov5675->exposure->minimum,
 					 exposure_max, ov5675->exposure->step,
@@ -689,7 +689,13 @@ static int ov5675_set_ctrl(struct v4l2_ctrl *ctrl)
 		break;
 
 	case V4L2_CID_EXPOSURE:
-		/* 3 least significant bits of expsoure are fractional part */
+		/* 4 least significant bits of expsoure are fractional part
+		 * val = val << 4
+		 * for ov5675, the unit of exposure is differnt from other
+		 * OmniVision sensors, its exposure value is twice of the
+		 * register value, the exposure should be divided by 2 before
+		 * set register, e.g. val << 3.
+		 */
 		ret = ov5675_write_reg(ov5675, OV5675_REG_EXPOSURE,
 				       OV5675_REG_VALUE_24BIT, ctrl->val << 3);
 		break;
@@ -770,8 +776,7 @@ static int ov5675_init_controls(struct ov5675 *ov5675)
 	v4l2_ctrl_new_std(ctrl_hdlr, &ov5675_ctrl_ops, V4L2_CID_DIGITAL_GAIN,
 			  OV5675_DGTL_GAIN_MIN, OV5675_DGTL_GAIN_MAX,
 			  OV5675_DGTL_GAIN_STEP, OV5675_DGTL_GAIN_DEFAULT);
-	exposure_max = (ov5675->cur_mode->vts_def -
-			OV5675_EXPOSURE_MAX_MARGIN) / 2;
+	exposure_max = (ov5675->cur_mode->vts_def - OV5675_EXPOSURE_MAX_MARGIN);
 	ov5675->exposure = v4l2_ctrl_new_std(ctrl_hdlr, &ov5675_ctrl_ops,
 					     V4L2_CID_EXPOSURE,
 					     OV5675_EXPOSURE_MIN, exposure_max,