--- zzzz-none-000/linux-3.10.107/Documentation/input/elantech.txt	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/Documentation/input/elantech.txt	2021-02-04 17:41:59.000000000 +0000
@@ -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