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linux/Documentation/input/elantech.txt
Florian Ragwitz e938fbfd4a Input: elantech - ignore high bits in the position coordinates 
In older versions of the elantech hardware/firmware those bits always
were unset, so it didn't actually matter, but newer versions seem to
use those high bits for something else, screwing up the coordinates
we report to the input layer for those devices.

Signed-off-by: Florian Ragwitz <rafl@debian.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2010-05-03 23:35:11 -07:00

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Elantech Touchpad Driver
========================
Copyright (C) 2007-2008 Arjan Opmeer <arjan@opmeer.net>
Extra information for hardware version 1 found and
provided by Steve Havelka
Version 2 (EeePC) hardware support based on patches
received from Woody at Xandros and forwarded to me
by user StewieGriffin at the eeeuser.com forum
Contents
~~~~~~~~
1. Introduction
2. Extra knobs
3. Hardware version 1
3.1 Registers
3.2 Native relative mode 4 byte packet format
3.3 Native absolute mode 4 byte packet format
4. Hardware version 2
4.1 Registers
4.2 Native absolute mode 6 byte packet format
4.2.1 One finger touch
4.2.2 Two finger touch
1. Introduction
~~~~~~~~~~~~
Currently the Linux Elantech touchpad driver is aware of two different
hardware versions unimaginatively called version 1 and version 2. Version 1
is found in "older" laptops and uses 4 bytes per packet. Version 2 seems to
be introduced with the EeePC and uses 6 bytes per packet.
The driver tries to support both hardware versions and should be compatible
with the Xorg Synaptics touchpad driver and its graphical configuration
utilities.
Additionally the operation of the touchpad can be altered by adjusting the
contents of some of its internal registers. These registers are represented
by the driver as sysfs entries under /sys/bus/serio/drivers/psmouse/serio?
that can be read from and written to.
Currently only the registers for hardware version 1 are somewhat understood.
Hardware version 2 seems to use some of the same registers but it is not
known whether the bits in the registers represent the same thing or might
have changed their meaning.
On top of that, some register settings have effect only when the touchpad is
in relative mode and not in absolute mode. As the Linux Elantech touchpad
driver always puts the hardware into absolute mode not all information
mentioned below can be used immediately. But because there is no freely
available Elantech documentation the information is provided here anyway for
completeness sake.
/////////////////////////////////////////////////////////////////////////////
2. Extra knobs
~~~~~~~~~~~
Currently the Linux Elantech touchpad driver provides two extra knobs under
/sys/bus/serio/drivers/psmouse/serio? for the user.
* debug
Turn different levels of debugging ON or OFF.
By echoing "0" to this file all debugging will be turned OFF.
Currently a value of "1" will turn on some basic debugging and a value of
"2" will turn on packet debugging. For hardware version 1 the default is
OFF. For version 2 the default is "1".
Turning packet debugging on will make the driver dump every packet
received to the syslog before processing it. Be warned that this can
generate quite a lot of data!
* paritycheck
Turns parity checking ON or OFF.
By echoing "0" to this file parity checking will be turned OFF. Any
non-zero value will turn it ON. For hardware version 1 the default is ON.
For version 2 the default it is OFF.
Hardware version 1 provides basic data integrity verification by
calculating a parity bit for the last 3 bytes of each packet. The driver
can check these bits and reject any packet that appears corrupted. Using
this knob you can bypass that check.
It is not known yet whether hardware version 2 provides the same parity
bits. Hence checking is disabled by default. Currently even turning it on
will do nothing.
/////////////////////////////////////////////////////////////////////////////
3. Hardware version 1
==================
3.1 Registers
~~~~~~~~~
By echoing a hexadecimal value to a register it contents can be altered.
For example:
echo -n 0x16 > reg_10
* reg_10
bit 7 6 5 4 3 2 1 0
B C T D L A S E
E: 1 = enable smart edges unconditionally
S: 1 = enable smart edges only when dragging
A: 1 = absolute mode (needs 4 byte packets, see reg_11)
L: 1 = enable drag lock (see reg_22)
D: 1 = disable dynamic resolution
T: 1 = disable tapping
C: 1 = enable corner tap
B: 1 = swap left and right button
* reg_11
bit 7 6 5 4 3 2 1 0
1 0 0 H V 1 F P
P: 1 = enable parity checking for relative mode
F: 1 = enable native 4 byte packet mode
V: 1 = enable vertical scroll area
H: 1 = enable horizontal scroll area
* reg_20
single finger width?
* reg_21
scroll area width (small: 0x40 ... wide: 0xff)
* reg_22
drag lock time out (short: 0x14 ... long: 0xfe;
0xff = tap again to release)
* reg_23
tap make timeout?
* reg_24
tap release timeout?
* reg_25
smart edge cursor speed (0x02 = slow, 0x03 = medium, 0x04 = fast)
* reg_26
smart edge activation area width?
3.2 Native relative mode 4 byte packet format
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
byte 0:
bit 7 6 5 4 3 2 1 0
c c p2 p1 1 M R L
L, R, M = 1 when Left, Right, Middle mouse button pressed
some models have M as byte 3 odd parity bit
when parity checking is enabled (reg_11, P = 1):
p1..p2 = byte 1 and 2 odd parity bit
c = 1 when corner tap detected
byte 1:
bit 7 6 5 4 3 2 1 0
dx7 dx6 dx5 dx4 dx3 dx2 dx1 dx0
dx7..dx0 = x movement; positive = right, negative = left
byte 1 = 0xf0 when corner tap detected
byte 2:
bit 7 6 5 4 3 2 1 0
dy7 dy6 dy5 dy4 dy3 dy2 dy1 dy0
dy7..dy0 = y movement; positive = up, negative = down
byte 3:
parity checking enabled (reg_11, P = 1):
bit 7 6 5 4 3 2 1 0
w h n1 n0 ds3 ds2 ds1 ds0
normally:
ds3..ds0 = scroll wheel amount and direction
positive = down or left
negative = up or right
when corner tap detected:
ds0 = 1 when top right corner tapped
ds1 = 1 when bottom right corner tapped
ds2 = 1 when bottom left corner tapped
ds3 = 1 when top left corner tapped
n1..n0 = number of fingers on touchpad
only models with firmware 2.x report this, models with
firmware 1.x seem to map one, two and three finger taps
directly to L, M and R mouse buttons
h = 1 when horizontal scroll action
w = 1 when wide finger touch?
otherwise (reg_11, P = 0):
bit 7 6 5 4 3 2 1 0
ds7 ds6 ds5 ds4 ds3 ds2 ds1 ds0
ds7..ds0 = vertical scroll amount and direction
negative = up
positive = down
3.3 Native absolute mode 4 byte packet format
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
byte 0:
firmware version 1.x:
bit 7 6 5 4 3 2 1 0
D U p1 p2 1 p3 R L
L, R = 1 when Left, Right mouse button pressed
p1..p3 = byte 1..3 odd parity bit
D, U = 1 when rocker switch pressed Up, Down
firmware version 2.x:
bit 7 6 5 4 3 2 1 0
n1 n0 p2 p1 1 p3 R L
L, R = 1 when Left, Right mouse button pressed
p1..p3 = byte 1..3 odd parity bit
n1..n0 = number of fingers on touchpad
byte 1:
firmware version 1.x:
bit 7 6 5 4 3 2 1 0
f 0 th tw x9 x8 y9 y8
tw = 1 when two finger touch
th = 1 when three finger touch
f = 1 when finger touch
firmware version 2.x:
bit 7 6 5 4 3 2 1 0
. . . . x9 x8 y9 y8
byte 2:
bit 7 6 5 4 3 2 1 0
x7 x6 x5 x4 x3 x2 x1 x0
x9..x0 = absolute x value (horizontal)
byte 3:
bit 7 6 5 4 3 2 1 0
y7 y6 y5 y4 y3 y2 y1 y0
y9..y0 = absolute y value (vertical)
/////////////////////////////////////////////////////////////////////////////
4. Hardware version 2
==================
4.1 Registers
~~~~~~~~~
By echoing a hexadecimal value to a register it contents can be altered.
For example:
echo -n 0x56 > reg_10
* reg_10
bit 7 6 5 4 3 2 1 0
0 1 0 1 0 1 D 0
D: 1 = enable drag and drop
* reg_11
bit 7 6 5 4 3 2 1 0
1 0 0 0 S 0 1 0
S: 1 = enable vertical scroll
* reg_21
unknown (0x00)
* reg_22
drag and drop release time out (short: 0x70 ... long 0x7e;
0x7f = never i.e. tap again to release)
4.2 Native absolute mode 6 byte packet format
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4.2.1 One finger touch
~~~~~~~~~~~~~~~~
byte 0:
bit 7 6 5 4 3 2 1 0
n1 n0 . . . . R L
L, R = 1 when Left, Right mouse button pressed
n1..n0 = numbers of fingers on touchpad
byte 1:
bit 7 6 5 4 3 2 1 0
. . . . . x10 x9 x8
byte 2:
bit 7 6 5 4 3 2 1 0
x7 x6 x5 x4 x4 x2 x1 x0
x10..x0 = absolute x value (horizontal)
byte 3:
bit 7 6 5 4 3 2 1 0
. . . . . . . .
byte 4:
bit 7 6 5 4 3 2 1 0
. . . . . . y9 y8
byte 5:
bit 7 6 5 4 3 2 1 0
y7 y6 y5 y4 y3 y2 y1 y0
y9..y0 = absolute y value (vertical)
4.2.2 Two finger touch
~~~~~~~~~~~~~~~~
byte 0:
bit 7 6 5 4 3 2 1 0
n1 n0 ay8 ax8 . . R L
L, R = 1 when Left, Right mouse button pressed
n1..n0 = numbers of fingers on touchpad
byte 1:
bit 7 6 5 4 3 2 1 0
ax7 ax6 ax5 ax4 ax3 ax2 ax1 ax0
ax8..ax0 = first finger absolute x value
byte 2:
bit 7 6 5 4 3 2 1 0
ay7 ay6 ay5 ay4 ay3 ay2 ay1 ay0
ay8..ay0 = first finger absolute y value
byte 3:
bit 7 6 5 4 3 2 1 0
. . by8 bx8 . . . .
byte 4:
bit 7 6 5 4 3 2 1 0
bx7 bx6 bx5 bx4 bx3 bx2 bx1 bx0
bx8..bx0 = second finger absolute x value
byte 5:
bit 7 6 5 4 3 2 1 0
by7 by8 by5 by4 by3 by2 by1 by0
by8..by0 = second finger absolute y value
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