Re: [PATCH 5/7] drivers:input:ads7846(+tsc2046): add new common binding names, pre-calibration and flipping

[Rob Herring]

On Fri, Nov 06, 2015 at 04:14:47PM +0100, H. Nikolaus Schaller wrote:
> commit b98abe52fa8e ("Input: add common DT binding for touchscreens")
> introduced common DT bindings for touchscreens [1] and a helper function to
> parse the DT.
> 
> This has been integrated and interpretation of the inversion (flipping)
> properties for the x and y axis has been added to accommodate any
> orientation of the touch in relation to the LCD.
> 
> By scaling the min/max ADC values to the screen size it is now possible to
> pre-calibrate the touch so that is (almost) exactly matches the LCD it is
> glued onto. This allows to well enough operate the touch before a user
> space calibration can improve the precision.
> 
> [1]: Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt
> 
> Signed-off-by: H. Nikolaus Schaller 
> ---
>  .../devicetree/bindings/input/ads7846.txt  |  8 ++-

The binding change looks okay, but...

> @@ -1213,7 +1259,7 @@ static const struct ads7846_platform_data 
> *ads7846_probe_dt(struct device *dev)
>   of_property_read_u16(node, "ti,vref-mv", >vref_mv);
>   pdata->keep_vref_on = of_property_read_bool(node, "ti,keep-vref-on");
>  
> - pdata->swap_xy = of_property_read_bool(node, "ti,swap-xy");
> + pdata->swap_xy = of_property_read_bool(node, "touchscreen-swapped-x-y");

This will break with old dtb's. The driver should look for either 
property.

Rob
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Re: [PATCH 5/7] drivers:input:ads7846(+tsc2046): add new common binding names, pre-calibration and flipping

[H. Nikolaus Schaller]

Am 09.11.2015 um 18:31 schrieb Rob Herring :

> On Fri, Nov 06, 2015 at 04:14:47PM +0100, H. Nikolaus Schaller wrote:
>> commit b98abe52fa8e ("Input: add common DT binding for touchscreens")
>> introduced common DT bindings for touchscreens [1] and a helper function to
>> parse the DT.
>> 
>> This has been integrated and interpretation of the inversion (flipping)
>> properties for the x and y axis has been added to accommodate any
>> orientation of the touch in relation to the LCD.
>> 
>> By scaling the min/max ADC values to the screen size it is now possible to
>> pre-calibrate the touch so that is (almost) exactly matches the LCD it is
>> glued onto. This allows to well enough operate the touch before a user
>> space calibration can improve the precision.
>> 
>> [1]: Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt
>> 
>> Signed-off-by: H. Nikolaus Schaller 
>> ---
>> .../devicetree/bindings/input/ads7846.txt  |  8 ++-
> 
> The binding change looks okay, but...
> 
>> @@ -1213,7 +1259,7 @@ static const struct ads7846_platform_data 
>> *ads7846_probe_dt(struct device *dev)
>>  of_property_read_u16(node, "ti,vref-mv", >vref_mv);
>>  pdata->keep_vref_on = of_property_read_bool(node, "ti,keep-vref-on");
>> 
>> -pdata->swap_xy = of_property_read_bool(node, "ti,swap-xy");
>> +pdata->swap_xy = of_property_read_bool(node, "touchscreen-swapped-x-y");
> 
> This will break with old dtb's.

We have a patch for all boards in tree (external dtbs must be modified by their 
maintainers).

> The driver should look for either 
> property.

It is easy to recognize either one.

Noted for V2.

BR and thanks,
Nikolaus--
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[PATCH 5/7] drivers:input:ads7846(+tsc2046): add new common binding names, pre-calibration and flipping

[H. Nikolaus Schaller]

commit b98abe52fa8e ("Input: add common DT binding for touchscreens")
introduced common DT bindings for touchscreens [1] and a helper function to
parse the DT.

This has been integrated and interpretation of the inversion (flipping)
properties for the x and y axis has been added to accommodate any
orientation of the touch in relation to the LCD.

By scaling the min/max ADC values to the screen size it is now possible to
pre-calibrate the touch so that is (almost) exactly matches the LCD it is
glued onto. This allows to well enough operate the touch before a user
space calibration can improve the precision.

[1]: Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt

Signed-off-by: H. Nikolaus Schaller 
---
 .../devicetree/bindings/input/ads7846.txt  |  8 ++-
 drivers/input/touchscreen/ads7846.c| 72 --
 2 files changed, 74 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/input/ads7846.txt 
b/Documentation/devicetree/bindings/input/ads7846.txt
index df8b127..ae56355 100644
--- a/Documentation/devicetree/bindings/input/ads7846.txt
+++ b/Documentation/devicetree/bindings/input/ads7846.txt
@@ -26,12 +26,17 @@ Additional required properties:
 
 Optional properties:
 
+You can optionally specify any of the touchscreen parameters described in
+
+   Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt
+
+This allows to scale, invert or swap coordinates and define the fuzz factors.
+
ti,vref-delay-usecs vref supply delay in usecs, 0 for
external vref (u16).
ti,vref-mv  The VREF voltage, in millivolts (u16).
ti,keep-vref-on set to keep vref on for differential
measurements as well
-   ti,swap-xy  swap x and y axis
ti,settle-delay-usecSettling time of the analog signals;
a function of Vcc and the capacitance
on the X/Y drivers.  If set to non-zero,
@@ -79,6 +84,7 @@ Example for a TSC2046 chip connected to an McSPI controller 
of an OMAP SoC::
pendown-gpio = < 8 0>;
vcc-supply = <_vcc3>;
 
+   touchscreen-swapped-x-y;
ti,x-min = /bits/ 16 <0>;
ti,x-max = /bits/ 16 <8000>;
ti,y-min = /bits/ 16 <0>;
diff --git a/drivers/input/touchscreen/ads7846.c 
b/drivers/input/touchscreen/ads7846.c
index 04edc8f..4525f00 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -34,6 +34,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 
 /*
@@ -109,8 +110,14 @@ struct ads7846 {
u16 vref_delay_usecs;
u16 x_plate_ohms;
u16 pressure_max;
+   u16 x_min;
+   u16 x_max;
+   u16 y_min;
+   u16 y_max;
 
boolswap_xy;
+   boolinvert_x;
+   boolinvert_y;
booluse_internal;
 
struct ads7846_packet   *packet;
@@ -828,9 +835,48 @@ static void ads7846_report_state(struct ads7846 *ts)
if (Rt) {
struct input_dev *input = ts->input;
 
+   dev_dbg(>spi->dev,
+   "Raw point(%4d,%4d), pressure (%4u)\n",
+   x, y, Rt);
+   /* clamp to expected ADC range */
+   if (x < ts->x_min)
+   x = ts->x_min;
+   if (x > ts->x_max)
+   x = ts->x_max;
+   if (y < ts->y_min)
+   y = ts->y_min;
+   if (y > ts->y_max)
+   y = ts->y_max;
+
+   dev_dbg(>spi->dev,
+   "Clamped point(%4d,%4d), pressure (%4u)\n",
+   x, y, Rt);
+
+   /* flip */
+   if (ts->invert_x)
+   x = (ts->x_max - x) + ts->x_min;
+   if (ts->invert_y)
+   y = (ts->y_max - y) + ts->y_min;
+
+   dev_dbg(>spi->dev,
+   "Flipped point(%4d,%4d), pressure (%4u)\n",
+   x, y, Rt);
+
+   /* scale to desired output range */
+   x = (input->absinfo[ABS_X].maximum * (x - ts->x_min))
+   / (ts->x_max - ts->x_min);
+   y = (input->absinfo[ABS_Y].maximum * (y - ts->y_min))
+   / (ts->y_max - ts->y_min);
+
+   dev_dbg(>spi->dev,
+   "Scaled point(%4d,%4d), pressure (%4u)\n",
+   x, y, Rt);
+
+