Input: elantech - update the documentation
A chapter is added to describe the trackpoint packets.
A section is added to describe the behaviour of the knob crc_enabled in
sysfs.
The introduction of the documentation only mentioned v1/v2, but in the
last part it already contains explanation of v3 and v4. The introduction
is updated.
Signed-off-by: Ulrik De Bie <ulrik.debie-os@e2big.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
diff --git a/Documentation/input/elantech.txt b/Documentation/input/elantech.txt
index e1ae127..1ec0db7 100644
--- a/Documentation/input/elantech.txt
+++ b/Documentation/input/elantech.txt
@@ -38,22 +38,38 @@
7.2.1 Status packet
7.2.2 Head packet
7.2.3 Motion packet
+ 8. Trackpoint (for Hardware version 3 and 4)
+ 8.1 Registers
+ 8.2 Native relative mode 6 byte packet format
+ 8.2.1 Status Packet
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, and provides
-additional features such as position of two fingers, and width of the touch.
+Currently the Linux Elantech touchpad driver is aware of four different
+hardware versions unimaginatively called version 1,version 2, version 3
+and version 4. 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, and provides additional features such as position of two fingers,
+and width of the touch. Hardware version 3 uses 6 bytes per packet (and
+for 2 fingers the concatenation of two 6 bytes packets) and allows tracking
+of up to 3 fingers. Hardware version 4 uses 6 bytes per packet, and can
+combine a status packet with multiple head or motion packets. Hardware version
+4 allows tracking up to 5 fingers.
+
+Some Hardware version 3 and version 4 also have a trackpoint which uses a
+separate packet format. It is also 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.
+Note that a mouse button is also associated with either the touchpad or the
+trackpoint when a trackpoint is available. Disabling the Touchpad in xorg
+(TouchPadOff=0) will also disable the buttons associated with the touchpad.
+
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?
@@ -78,7 +94,7 @@
2. Extra knobs
~~~~~~~~~~~
-Currently the Linux Elantech touchpad driver provides two extra knobs under
+Currently the Linux Elantech touchpad driver provides three extra knobs under
/sys/bus/serio/drivers/psmouse/serio? for the user.
* debug
@@ -112,6 +128,20 @@
data consistency checking can be done. For now checking is disabled by
default. Currently even turning it on will do nothing.
+* crc_enabled
+
+ Sets crc_enabled to 0/1. The name "crc_enabled" is the official name of
+ this integrity check, even though it is not an actual cyclic redundancy
+ check.
+
+ Depending on the state of crc_enabled, certain basic data integrity
+ verification is done by the driver on hardware version 3 and 4. The
+ driver will reject any packet that appears corrupted. Using this knob,
+ The state of crc_enabled can be altered with this knob.
+
+ Reading the crc_enabled value will show the active value. Echoing
+ "0" or "1" to this file will set the state to "0" or "1".
+
/////////////////////////////////////////////////////////////////////////////
3. Differentiating hardware versions
@@ -746,3 +776,42 @@
byte 0 ~ 2 for one finger
byte 3 ~ 5 for another
+
+
+8. Trackpoint (for Hardware version 3 and 4)
+ =========================================
+8.1 Registers
+ ~~~~~~~~~
+No special registers have been identified.
+
+8.2 Native relative mode 6 byte packet format
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+8.2.1 Status Packet
+ ~~~~~~~~~~~~~
+
+byte 0:
+ bit 7 6 5 4 3 2 1 0
+ 0 0 sx sy 0 M R L
+byte 1:
+ bit 7 6 5 4 3 2 1 0
+ ~sx 0 0 0 0 0 0 0
+byte 2:
+ bit 7 6 5 4 3 2 1 0
+ ~sy 0 0 0 0 0 0 0
+byte 3:
+ bit 7 6 5 4 3 2 1 0
+ 0 0 ~sy ~sx 0 1 1 0
+byte 4:
+ bit 7 6 5 4 3 2 1 0
+ x7 x6 x5 x4 x3 x2 x1 x0
+byte 5:
+ bit 7 6 5 4 3 2 1 0
+ y7 y6 y5 y4 y3 y2 y1 y0
+
+
+ x and y are written in two's complement spread
+ over 9 bits with sx/sy the relative top bit and
+ x7..x0 and y7..y0 the lower bits.
+ ~sx is the inverse of sx, ~sy is the inverse of sy.
+ The sign of y is opposite to what the input driver
+ expects for a relative movement