input : wacom_w8001 - report resolution to userland

Serial devices send both pen and touch data through the same logical port. Since we scaled touch to pen maximum, we use pen resolution for touch as well here.

This is under the assumption that pen and touch share the same physical surface. In the case when a small physical dimensional difference occurs between pen and touch, we assume the tolerance for touch point precision is higher than pen and the difference is within touch point tolerance.

A per-MT tool based resolution mechanism should be introduced if the above assumption does not hold true for the pen and touch devices any more. A good candidate to resolve this issue without introducing design change could be to report touch resolution through ABS_MT_POSITION_X/Y.

This version corrected an oversimplified if statement in v2.

Signed-off-by Ping Cheng <[email protected]>

---

 drivers/input/touchscreen/wacom_w8001.c |   20 +++++++++++++++-----
 1 files changed, 15 insertions(+), 5 deletions(-)

drivers/input/touchscreen/wacom_w8001.c +7 -1

index 5cb8449..68dcca0 100644
@@ -51,6 +51,10 @@ MODULE_LICENSE("GPL");
 #define W8001_PKTLEN_TPCCTL	11	/* control packet */
 #define W8001_PKTLEN_TOUCH2FG	13
 
+/* resolution in points/mm */
+#define W8001_PEN_RESOLUTION    100
+#define W8001_TOUCH_RESOLUTION  10
+
 struct w8001_coord {
 	u8 rdy;
 	u8 tsw;

@@ -198,7 +202,7 @@ static void parse_touchquery(u8 *data, struct w8001_touch_query *query)
 		query->y = 1024;
 		if (query->panel_res)
 			query->x = query->y = (1 << query->panel_res);
-		query->panel_res = 10;
+		query->panel_res = W8001_TOUCH_RESOLUTION;
 	}
 }
 

@@ -394,6 +398,8 @@ static int w8001_setup(struct w8001 *w8001)
 
 		input_set_abs_params(dev, ABS_X, 0, coord.x, 0, 0);
 		input_set_abs_params(dev, ABS_Y, 0, coord.y, 0, 0);
+		input_abs_set_res(dev, ABS_X, W8001_PEN_RESOLUTION);
+		input_abs_set_res(dev, ABS_Y, W8001_PEN_RESOLUTION);
 		input_set_abs_params(dev, ABS_PRESSURE, 0, coord.pen_pressure, 0, 0);
 		if (coord.tilt_x && coord.tilt_y) {
 			input_set_abs_params(dev, ABS_TILT_X, 0, coord.tilt_x, 0, 0);

drivers/input/touchscreen/wacom_w8001.c +4 -0

+		} else { /* touch only */
+			/* set axes with touch data */
+			input_set_abs_params(dev, ABS_X, 0, touch.x, 0, 0);
+			input_set_abs_params(dev, ABS_Y, 0, touch.y, 0, 0);

Hi Ping,

Quoted 9 lines · Ping Cheng

Serial devices send both pen and touch data through the same logical port. Since we scaled touch to pen maximum, we use pen resolution for touch as well here.

This is under the assumption that pen and touch share the same physical surface. In the case when a small physical dimensional difference occurs between pen and touch, we assume the tolerance for touch point precision is higher than pen and the difference is within touch point tolerance.

Quoted 4 lines

A per-MT tool based resolution mechanism should be introduced if the above assumption does not hold true for the pen and touch devices any more. A good candidate to resolve this issue without introducing design change could be to report touch resolution through ABS_MT_POSITION_X/Y.

This still sounds a bit like mixing apples and oranges. If this case would ever happen, and I doubt it since the whole idea is to use different tools on the same surface, then splitting into separate devices would be appropriate.

Quoted 43 lines

This version corrected an oversimplified if statement in v2.

Signed-off-by Ping Cheng <[email protected]>

---

 drivers/input/touchscreen/wacom_w8001.c |   20 +++++++++++++++-----
 1 files changed, 15 insertions(+), 5 deletions(-)

drivers/input/touchscreen/wacom_w8001.c +7 -1

index 5cb8449..68dcca0 100644
@@ -51,6 +51,10 @@ MODULE_LICENSE("GPL");
 #define W8001_PKTLEN_TPCCTL	11	/* control packet */
 #define W8001_PKTLEN_TOUCH2FG	13
 
+/* resolution in points/mm */
+#define W8001_PEN_RESOLUTION    100
+#define W8001_TOUCH_RESOLUTION  10
+
 struct w8001_coord {
 	u8 rdy;
 	u8 tsw;

@@ -198,7 +202,7 @@ static void parse_touchquery(u8 *data, struct w8001_touch_query *query)
 		query->y = 1024;
 		if (query->panel_res)
 			query->x = query->y = (1 << query->panel_res);
-		query->panel_res = 10;
+		query->panel_res = W8001_TOUCH_RESOLUTION;
 	}
 }
 

@@ -394,6 +398,8 @@ static int w8001_setup(struct w8001 *w8001)
 
 		input_set_abs_params(dev, ABS_X, 0, coord.x, 0, 0);
 		input_set_abs_params(dev, ABS_Y, 0, coord.y, 0, 0);
+		input_abs_set_res(dev, ABS_X, W8001_PEN_RESOLUTION);
+		input_abs_set_res(dev, ABS_Y, W8001_PEN_RESOLUTION);
 		input_set_abs_params(dev, ABS_PRESSURE, 0, coord.pen_pressure, 0, 0);
 		if (coord.tilt_x && coord.tilt_y) {
 			input_set_abs_params(dev, ABS_TILT_X, 0, coord.tilt_x, 0, 0);

drivers/input/touchscreen/wacom_w8001.c static int w8001_setup(struct w8001 *w8001) · line 425

Quoted 2 lines

drivers/input/touchscreen/wacom_w8001.c +0 -0

@@ -418,15 +424,19 @@ static int w8001_setup(struct w8001 *w8001)
 		w8001->max_touch_x = touch.x;
 		w8001->max_touch_y = touch.y;

So max_touch is set here

drivers/input/touchscreen/wacom_w8001.c static int w8001_setup(struct w8001 *w8001) · line 430

Quoted 7 lines

drivers/input/touchscreen/wacom_w8001.c +2 -1

-		/* scale to pen maximum */
+		/* pen supported */
 		if (w8001->max_pen_x && w8001->max_pen_y) {
+			/* scale to pen maximum */
 			touch.x = w8001->max_pen_x;
 			touch.y = w8001->max_pen_y;

And possibly redefined here

Quoted 8 lines

drivers/input/touchscreen/wacom_w8001.c +6 -0

+		} else { /* touch only */
+			/* set axes with touch data */
+			input_set_abs_params(dev, ABS_X, 0, touch.x, 0, 0);
+			input_set_abs_params(dev, ABS_Y, 0, touch.y, 0, 0);
+			input_abs_set_res(dev, ABS_X, touch.panel_res);
+			input_abs_set_res(dev, ABS_Y, touch.panel_res);
 		}
 

drivers/input/touchscreen/wacom_w8001.c static int w8001_setup(struct w8001 *w8001) · line 441

Quoted 6 lines

drivers/input/touchscreen/wacom_w8001.c +0 -3

-		input_set_abs_params(dev, ABS_X, 0, touch.x, 0, 0);
-		input_set_abs_params(dev, ABS_Y, 0, touch.y, 0, 0);
-
 		switch (touch.sensor_id) {
 		case 0:
 		case 2:

And then just used to set MT later on, which will lead to ABS_MT_POSITION_X values different from ABS_X. This is just getting messier. In fact, the whole setup function is messy, with unclear handling of error paths. Any chance one could simplify the logic involved here? It should be possible to use a single code path for input_set_abs_params() and input_abs_set_res(), for instance.

Quoted 95 lines · Henrik Rydberg

Hi Ping,

Quoted 9 lines · Ping Cheng

Serial devices send both pen and touch data through the same logical port. Since we scaled touch to pen maximum, we use pen resolution for touch as well here.

This is under the assumption that pen and touch share the same physical surface. In the case when a small physical dimensional difference occurs between pen and touch, we assume the tolerance for touch point precision is higher than pen and the difference is within touch point tolerance.

Quoted 4 lines

A per-MT tool based resolution mechanism should be introduced if the above assumption does not hold true for the pen and touch devices any more. A good candidate to resolve this issue without introducing design change could be to report touch resolution through ABS_MT_POSITION_X/Y.

This still sounds a bit like mixing apples and oranges. If this case would ever happen, and I doubt it since the whole idea is to use different tools on the same surface, then splitting into separate devices would be appropriate.

Quoted 43 lines

This version corrected an oversimplified if statement in v2.

Signed-off-by Ping Cheng <[email protected]>

---

 drivers/input/touchscreen/wacom_w8001.c |   20 +++++++++++++++-----

 1 files changed, 15 insertions(+), 5 deletions(-)

drivers/input/touchscreen/wacom_w8001.c +7 -1

index 5cb8449..68dcca0 100644
@@ -51,6 +51,10 @@ MODULE_LICENSE("GPL");
  #define W8001_PKTLEN_TPCCTL        11      /* control packet */
  #define W8001_PKTLEN_TOUCH2FG      13
 
+/* resolution in points/mm */
+#define W8001_PEN_RESOLUTION    100
+#define W8001_TOUCH_RESOLUTION  10
+
  struct w8001_coord {
     u8 rdy;
     u8 tsw;

@@ -198,7 +202,7 @@ static void parse_touchquery(u8 *data, struct w8001_touch_query *query)
             query->y = 1024;
             if (query->panel_res)
                     query->x = query->y = (1 << query->panel_res);
-           query->panel_res = 10;
+           query->panel_res = W8001_TOUCH_RESOLUTION;
     }
  }
 

@@ -394,6 +398,8 @@ static int w8001_setup(struct w8001 *w8001)
 
             input_set_abs_params(dev, ABS_X, 0, coord.x, 0, 0);
             input_set_abs_params(dev, ABS_Y, 0, coord.y, 0, 0);
+           input_abs_set_res(dev, ABS_X, W8001_PEN_RESOLUTION);
+           input_abs_set_res(dev, ABS_Y, W8001_PEN_RESOLUTION);
             input_set_abs_params(dev, ABS_PRESSURE, 0, coord.pen_pressure, 0, 0);
             if (coord.tilt_x && coord.tilt_y) {
                     input_set_abs_params(dev, ABS_TILT_X, 0, coord.tilt_x, 0, 0);

drivers/input/touchscreen/wacom_w8001.c static int w8001_setup(struct w8001 *w8001) · line 425

Quoted 2 lines

drivers/input/touchscreen/wacom_w8001.c +0 -0

@@ -418,15 +424,19 @@ static int w8001_setup(struct w8001 *w8001)
             w8001->max_touch_x = touch.x;
             w8001->max_touch_y = touch.y;

So max_touch is set here

drivers/input/touchscreen/wacom_w8001.c static int w8001_setup(struct w8001 *w8001) · line 430

Quoted 7 lines

drivers/input/touchscreen/wacom_w8001.c +2 -1

-           /* scale to pen maximum */
+           /* pen supported */
             if (w8001->max_pen_x && w8001->max_pen_y) {
+                   /* scale to pen maximum */
                     touch.x = w8001->max_pen_x;
                     touch.y = w8001->max_pen_y;

And possibly redefined here

Quoted 12 lines

drivers/input/touchscreen/wacom_w8001.c +6 -3

+           } else { /* touch only */
+                   /* set axes with touch data */
+                   input_set_abs_params(dev, ABS_X, 0, touch.x, 0, 0);
+                   input_set_abs_params(dev, ABS_Y, 0, touch.y, 0, 0);
+                   input_abs_set_res(dev, ABS_X, touch.panel_res);
+                   input_abs_set_res(dev, ABS_Y, touch.panel_res);
             }
 
-           input_set_abs_params(dev, ABS_X, 0, touch.x, 0, 0);
-           input_set_abs_params(dev, ABS_Y, 0, touch.y, 0, 0);
-
             switch (touch.sensor_id) {

Quoted 2 lines

            case 0:
            case 2:

Quoted 7 lines

And then just used to set MT later on, which will lead to ABS_MT_POSITION_X values different from ABS_X. This is just getting messier. In fact, the whole setup function is messy, with unclear handling of error paths. Any chance one could simplify the logic involved here? It should be possible to use a single code path for input_set_abs_params() and input_abs_set_res(), for instance.

I have the following for the resolution reporting:

Input: wacom_w8001 - report resolution to userland

From: Ping Cheng <[email protected]>

Serial devices send both pen and touch data through the same logical port. Since we scaled touch to pen maximum, we use pen resolution for touch as well here.

This is under the assumption that pen and touch share the same physical surface. In the case when a small physical dimensional difference occurs between pen and touch, we assume the tolerance for touch point precision is higher than pen and the difference is within touch point tolerance.

A per-MT tool based resolution mechanism should be introduced if the above assumption does not hold true for the pen and touch devices any more.

Signed-off-by Ping Cheng <[email protected]>

Signed-off-by Dmitry Torokhov <[email protected]>

---

 drivers/input/touchscreen/wacom_w8001.c |   13 +++++++++++--

 1 files changed, 11 insertions(+), 2 deletions(-)

drivers/input/touchscreen/wacom_w8001.c +11 -2

index 5cb8449..c14412e 100644
@@ -51,6 +51,10 @@ MODULE_LICENSE("GPL");
  #define W8001_PKTLEN_TPCCTL    11      /* control packet */
  #define W8001_PKTLEN_TOUCH2FG  13
 
+/* resolution in points/mm */
+#define W8001_PEN_RESOLUTION    100
+#define W8001_TOUCH_RESOLUTION  10
+
  struct w8001_coord {
        u8 rdy;
        u8 tsw;

@@ -198,7 +202,7 @@ static void parse_touchquery(u8 *data, struct w8001_touch_query *query)
                query->y = 1024;
                if (query->panel_res)
                        query->x = query->y = (1 << query->panel_res);
-               query->panel_res = 10;
+               query->panel_res = W8001_TOUCH_RESOLUTION;
        }
  }
 

@@ -394,6 +398,8 @@ static int w8001_setup(struct w8001 *w8001)
 
                input_set_abs_params(dev, ABS_X, 0, coord.x, 0, 0);
                input_set_abs_params(dev, ABS_Y, 0, coord.y, 0, 0);
+               input_abs_set_res(dev, ABS_X, W8001_PEN_RESOLUTION);
+               input_abs_set_res(dev, ABS_Y, W8001_PEN_RESOLUTION);
                input_set_abs_params(dev, ABS_PRESSURE, 0, coord.pen_pressure, 0, 0);
                if (coord.tilt_x && coord.tilt_y) {
                        input_set_abs_params(dev, ABS_TILT_X, 0, coord.tilt_x, 0, 0);

@@ -418,14 +424,17 @@ static int w8001_setup(struct w8001 *w8001)
                w8001->max_touch_x = touch.x;
                w8001->max_touch_y = touch.y;
 
-               /* scale to pen maximum */
                if (w8001->max_pen_x && w8001->max_pen_y) {
+                       /* if pen is supported scale to pen maximum */
                        touch.x = w8001->max_pen_x;
                        touch.y = w8001->max_pen_y;
+                       touch.panel_res = W8001_PEN_RESOLUTION;
                }
 
                input_set_abs_params(dev, ABS_X, 0, touch.x, 0, 0);
                input_set_abs_params(dev, ABS_Y, 0, touch.y, 0, 0);
+               input_abs_set_res(dev, ABS_X, touch.panel_res);
+               input_abs_set_res(dev, ABS_Y, touch.panel_res);
 
                switch (touch.sensor_id) {

               case 0:
--
Dmitry

Quoted 1 line

I have the following for the resolution reporting:

It works for me. Although the end result is the same as the v3 since params and res have already been set in pen response blok if pen is supported, it is more straight forward in logical to anyone who tries to understand the code.

Thank you, Dmitry.