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Commit 4e904954 authored by Jason Gerecke's avatar Jason Gerecke Committed by Dmitry Torokhov
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Input: wacom - report correct touch contact size for I5/Bamboo 



This changes how the touch packets for Intuos5 and 3rd-gen Bamboo
are interpreted, so that proper values for the MAJOR and MINOR
axes are reported. Instead of using the amplitude field (data[6]),
we use the size field (data[5]) and do some calculation to
transform it from a scaled-down area into axis lengths.

Note that even though we assume a circular contact, both MAJOR and
MINOR are reported since the resolution of the X and Y axes differ.

Signed-off-by: default avatarJason Gerecke <killertofu@gmail.com>
Reviewed-by: default avatarChris Bagwell <chris@cnpbagwell.com>
Acked-by: default avatarPing Cheng <pingc@wacom.com>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 77740368

drivers/input/tablet/wacom_wac.c

+22 −4
Original line number Diff line number Diff line
@@ -25,6 +25,11 @@ 
#define WACOM_INTUOS_RES	100

#define WACOM_INTUOS3_RES	200



/* Scale factor relating reported contact size to logical contact area.

 * 2^14/pi is a good approximation on Intuos5 and 3rd-gen Bamboo

 */

#define WACOM_CONTACT_AREA_SCALE 2607



static int wacom_penpartner_irq(struct wacom_wac *wacom)

{

	unsigned char *data = wacom->data;
@@ -1043,11 +1048,19 @@ static void wacom_bpt3_touch_msg(struct wacom_wac *wacom, unsigned char *data) 
	if (touch) {

		int x = (data[2] << 4) | (data[4] >> 4);

		int y = (data[3] << 4) | (data[4] & 0x0f);

		int w = data[6];

		int a = data[5];



		// "a" is a scaled-down area which we assume is roughly

		// circular and which can be described as: a=(pi*r^2)/C.

		int x_res  = input_abs_get_res(input, ABS_X);

		int y_res  = input_abs_get_res(input, ABS_Y);

		int width  = 2 * int_sqrt(a * WACOM_CONTACT_AREA_SCALE);

		int height = width * y_res / x_res;



		input_report_abs(input, ABS_MT_POSITION_X, x);

		input_report_abs(input, ABS_MT_POSITION_Y, y);

		input_report_abs(input, ABS_MT_TOUCH_MAJOR, w);

		input_report_abs(input, ABS_MT_TOUCH_MAJOR, width);

		input_report_abs(input, ABS_MT_TOUCH_MINOR, height);

	}

}
@@ -1533,7 +1546,9 @@ int wacom_setup_input_capabilities(struct input_dev *input_dev, 
			input_mt_init_slots(input_dev, features->touch_max, 0);



			input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR,

			                     0, 255, 0, 0);

			                     0, features->x_max, 0, 0);

			input_set_abs_params(input_dev, ABS_MT_TOUCH_MINOR,

			                     0, features->y_max, 0, 0);



			input_set_abs_params(input_dev, ABS_MT_POSITION_X,

					     0, features->x_max,
@@ -1641,7 +1656,10 @@ int wacom_setup_input_capabilities(struct input_dev *input_dev, 


				input_set_abs_params(input_dev,

						     ABS_MT_TOUCH_MAJOR,

						     0, 255, 0, 0);

						     0, features->x_max, 0, 0);

				input_set_abs_params(input_dev,

						     ABS_MT_TOUCH_MINOR,

						     0, features->y_max, 0, 0);

			}



			input_set_abs_params(input_dev, ABS_MT_POSITION_X,