HID: wacom: Add fuzz factor to distance and tilt axes

The fuzz present on the distance and tilt axes is noticable when a puck is
present, and userspace (specifically libinput) would like the ability to
filter out the noise. To facilitate this, we assign a fuzz value of '1'
for the distance and tilt axes. This is large enough to cover most of the
natural variation in distance value as the puck is moved around, and
enough to cover the jitter in rotation (reported through tilt axes) when
the puck is left alone.

Signed-off-by: Jason Gerecke <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/wacom_sys.c

···
 	features->x_fuzz = 4;
 	features->y_fuzz = 4;
 	features->pressure_fuzz = 0;
-	features->distance_fuzz = 0;
+	features->distance_fuzz = 1;
+	features->tilt_fuzz = 1;
 
 	/*
 	 * The wireless device HID is basic and layout conflicts with

drivers/hid/wacom_wac.c

···
 	__set_bit(BTN_STYLUS2, input_dev->keybit);
 
 	input_set_abs_params(input_dev, ABS_DISTANCE,
-			     0, wacom_wac->features.distance_max, 0, 0);
+			     0, wacom_wac->features.distance_max, wacom_wac->features.distance_fuzz, 0);
 }
 
 static void wacom_setup_cintiq(struct wacom_wac *wacom_wac)
 {
 	struct input_dev *input_dev = wacom_wac->pen_input;
+	struct wacom_features *features = &wacom_wac->features;
 
 	wacom_setup_basic_pro_pen(wacom_wac);
 
···
 	__set_bit(BTN_TOOL_AIRBRUSH, input_dev->keybit);
 
 	input_set_abs_params(input_dev, ABS_WHEEL, 0, 1023, 0, 0);
-	input_set_abs_params(input_dev, ABS_TILT_X, -64, 63, 0, 0);
+	input_set_abs_params(input_dev, ABS_TILT_X, -64, 63, features->tilt_fuzz, 0);
 	input_abs_set_res(input_dev, ABS_TILT_X, 57);
-	input_set_abs_params(input_dev, ABS_TILT_Y, -64, 63, 0, 0);
+	input_set_abs_params(input_dev, ABS_TILT_Y, -64, 63, features->tilt_fuzz, 0);
 	input_abs_set_res(input_dev, ABS_TILT_Y, 57);
 }
 
···
 	case WACOM_G4:
 		input_set_abs_params(input_dev, ABS_DISTANCE, 0,
 					      features->distance_max,
-					      0, 0);
+					      features->distance_fuzz, 0);
 		/* fall through */
 
 	case GRAPHIRE:
···
 
 		input_set_abs_params(input_dev, ABS_DISTANCE, 0,
 				      features->distance_max,
-				      0, 0);
+				      features->distance_fuzz, 0);
 
 		input_set_abs_params(input_dev, ABS_Z, -900, 899, 0, 0);
 		input_abs_set_res(input_dev, ABS_Z, 287);
···
 			__set_bit(BTN_STYLUS2, input_dev->keybit);
 			input_set_abs_params(input_dev, ABS_DISTANCE, 0,
 				      features->distance_max,
-				      0, 0);
+				      features->distance_fuzz, 0);
 		}
 		break;
 	case BAMBOO_PAD:

drivers/hid/wacom_wac.h

···
 	int y_fuzz;
 	int pressure_fuzz;
 	int distance_fuzz;
+	int tilt_fuzz;
 	unsigned quirks;
 	unsigned touch_max;
 	int oVid;