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Commit f053ea8d authored by Dmitry Torokhov's avatar Dmitry Torokhov
Browse files

Pull input changes from Henrik Rydberg, including large update to 

atmel_mxt_ts driver by Daniel and MT protocol addition for win8 devices.

Conflicts:
	drivers/input/touchscreen/atmel_mxt_ts.c
parents 3c3416ab c45361a1

Documentation/input/multi-touch-protocol.txt

+92 −26
Original line number Diff line number Diff line
@@ -162,26 +162,48 @@ are divided into categories, to allow for partial implementation. The 
minimum set consists of ABS_MT_POSITION_X and ABS_MT_POSITION_Y, which

allows for multiple contacts to be tracked.  If the device supports it, the

ABS_MT_TOUCH_MAJOR and ABS_MT_WIDTH_MAJOR may be used to provide the size

of the contact area and approaching contact, respectively.

of the contact area and approaching tool, respectively.



The TOUCH and WIDTH parameters have a geometrical interpretation; imagine

looking through a window at someone gently holding a finger against the

glass.  You will see two regions, one inner region consisting of the part

of the finger actually touching the glass, and one outer region formed by

the perimeter of the finger. The diameter of the inner region is the

ABS_MT_TOUCH_MAJOR, the diameter of the outer region is

ABS_MT_WIDTH_MAJOR. Now imagine the person pressing the finger harder

against the glass. The inner region will increase, and in general, the

ratio ABS_MT_TOUCH_MAJOR / ABS_MT_WIDTH_MAJOR, which is always smaller than

unity, is related to the contact pressure. For pressure-based devices,

the perimeter of the finger. The center of the touching region (a) is

ABS_MT_POSITION_X/Y and the center of the approaching finger (b) is

ABS_MT_TOOL_X/Y. The touch diameter is ABS_MT_TOUCH_MAJOR and the finger

diameter is ABS_MT_WIDTH_MAJOR. Now imagine the person pressing the finger

harder against the glass. The touch region will increase, and in general,

the ratio ABS_MT_TOUCH_MAJOR / ABS_MT_WIDTH_MAJOR, which is always smaller

than unity, is related to the contact pressure. For pressure-based devices,

ABS_MT_PRESSURE may be used to provide the pressure on the contact area

instead. Devices capable of contact hovering can use ABS_MT_DISTANCE to

indicate the distance between the contact and the surface.



In addition to the MAJOR parameters, the oval shape of the contact can be

described by adding the MINOR parameters, such that MAJOR and MINOR are the

major and minor axis of an ellipse. Finally, the orientation of the oval

shape can be describe with the ORIENTATION parameter.



	  Linux MT                               Win8

         __________                     _______________________

        /          \                   |                       |

       /            \                  |                       |

      /     ____     \                 |                       |

     /     /    \     \                |                       |

     \     \  a  \     \               |       a               |

      \     \____/      \              |                       |

       \                 \             |                       |

        \        b        \            |           b           |

         \                 \           |                       |

          \                 \          |                       |

           \                 \         |                       |

            \                /         |                       |

             \              /          |                       |

              \            /           |                       |

               \__________/            |_______________________|





In addition to the MAJOR parameters, the oval shape of the touch and finger

regions can be described by adding the MINOR parameters, such that MAJOR

and MINOR are the major and minor axis of an ellipse. The orientation of

the touch ellipse can be described with the ORIENTATION parameter, and the

direction of the finger ellipse is given by the vector (a - b).



For type A devices, further specification of the touch shape is possible

via ABS_MT_BLOB_ID.
@@ -224,7 +246,7 @@ tool. Omit if circular [4]. 
The above four values can be used to derive additional information about

the contact. The ratio ABS_MT_TOUCH_MAJOR / ABS_MT_WIDTH_MAJOR approximates

the notion of pressure. The fingers of the hand and the palm all have

different characteristic widths [1].

different characteristic widths.



ABS_MT_PRESSURE
@@ -240,17 +262,24 @@ the contact is hovering above the surface. 


ABS_MT_ORIENTATION



The orientation of the ellipse. The value should describe a signed quarter

of a revolution clockwise around the touch center. The signed value range

is arbitrary, but zero should be returned for a finger aligned along the Y

axis of the surface, a negative value when finger is turned to the left, and

a positive value when finger turned to the right. When completely aligned with

the X axis, the range max should be returned.  Orientation can be omitted

if the touching object is circular, or if the information is not available

in the kernel driver. Partial orientation support is possible if the device

can distinguish between the two axis, but not (uniquely) any values in

between. In such cases, the range of ABS_MT_ORIENTATION should be [0, 1]

[4].

The orientation of the touching ellipse. The value should describe a signed

quarter of a revolution clockwise around the touch center. The signed value

range is arbitrary, but zero should be returned for an ellipse aligned with

the Y axis of the surface, a negative value when the ellipse is turned to

the left, and a positive value when the ellipse is turned to the

right. When completely aligned with the X axis, the range max should be

returned.



Touch ellipsis are symmetrical by default. For devices capable of true 360

degree orientation, the reported orientation must exceed the range max to

indicate more than a quarter of a revolution. For an upside-down finger,

range max * 2 should be returned.



Orientation can be omitted if the touch area is circular, or if the

information is not available in the kernel driver. Partial orientation

support is possible if the device can distinguish between the two axis, but

not (uniquely) any values in between. In such cases, the range of

ABS_MT_ORIENTATION should be [0, 1] [4].



ABS_MT_POSITION_X
@@ -260,6 +289,23 @@ ABS_MT_POSITION_Y 


The surface Y coordinate of the center of the touching ellipse.



ABS_MT_TOOL_X



The surface X coordinate of the center of the approaching tool. Omit if

the device cannot distinguish between the intended touch point and the

tool itself.



ABS_MT_TOOL_Y



The surface Y coordinate of the center of the approaching tool. Omit if the

device cannot distinguish between the intended touch point and the tool

itself.



The four position values can be used to separate the position of the touch

from the position of the tool. If both positions are present, the major

tool axis points towards the touch point [1]. Otherwise, the tool axes are

aligned with the touch axes.



ABS_MT_TOOL_TYPE



The type of approaching tool. A lot of kernel drivers cannot distinguish
@@ -305,6 +351,28 @@ The range of ABS_MT_ORIENTATION should be set to [0, 1], to indicate that 
the device can distinguish between a finger along the Y axis (0) and a

finger along the X axis (1).



For win8 devices with both T and C coordinates, the position mapping is



   ABS_MT_POSITION_X := T_X

   ABS_MT_POSITION_Y := T_Y

   ABS_MT_TOOL_X := C_X

   ABS_MT_TOOL_X := C_Y



Unfortunately, there is not enough information to specify both the touching

ellipse and the tool ellipse, so one has to resort to approximations.  One

simple scheme, which is compatible with earlier usage, is:



   ABS_MT_TOUCH_MAJOR := min(X, Y)

   ABS_MT_TOUCH_MINOR := <not used>

   ABS_MT_ORIENTATION := <not used>

   ABS_MT_WIDTH_MAJOR := min(X, Y) + distance(T, C)

   ABS_MT_WIDTH_MINOR := min(X, Y)



Rationale: We have no information about the orientation of the touching

ellipse, so approximate it with an inscribed circle instead. The tool

ellipse should align with the the vector (T - C), so the diameter must

increase with distance(T, C). Finally, assume that the touch diameter is

equal to the tool thickness, and we arrive at the formulas above.



Finger Tracking

---------------
@@ -338,9 +406,7 @@ subsequent events of the same type refer to different fingers. 
For example usage of the type A protocol, see the bcm5974 driver. For

example usage of the type B protocol, see the hid-egalax driver.



[1] With the extension ABS_MT_APPROACH_X and ABS_MT_APPROACH_Y, the

difference between the contact position and the approaching tool position

could be used to derive tilt.

[1] Also, the difference (TOOL_X - POSITION_X) can be used to model tilt.

[2] The list can of course be extended.

[3] The mtdev project: http://bitmath.org/code/mtdev/.

[4] See the section on event computation.

drivers/input/input-mt.c

+1 −1
Original line number Diff line number Diff line
@@ -135,7 +135,7 @@ EXPORT_SYMBOL(input_mt_report_finger_count); 
 */

void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)

{

	struct input_mt_slot *oldest = 0;

	struct input_mt_slot *oldest = NULL;

	int oldid = dev->trkid;

	int count = 0;

	int i;