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>hifive-unleashed-5.1
Ulrik De Bie
Dmitry Torokhov
parent
2d9eb81fdb
commit
c6c748ef85
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@ -38,22 +38,38 @@ Contents
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7.2.1 Status packet
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7.2.2 Head packet
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7.2.3 Motion packet
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8. Trackpoint (for Hardware version 3 and 4)
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8.1 Registers
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8.2 Native relative mode 6 byte packet format
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8.2.1 Status Packet
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1. Introduction
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~~~~~~~~~~~~
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Currently the Linux Elantech touchpad driver is aware of two different
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hardware versions unimaginatively called version 1 and version 2. Version 1
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is found in "older" laptops and uses 4 bytes per packet. Version 2 seems to
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be introduced with the EeePC and uses 6 bytes per packet, and provides
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additional features such as position of two fingers, and width of the touch.
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Currently the Linux Elantech touchpad driver is aware of four different
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hardware versions unimaginatively called version 1,version 2, version 3
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and version 4. Version 1 is found in "older" laptops and uses 4 bytes per
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packet. Version 2 seems to be introduced with the EeePC and uses 6 bytes
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per packet, and provides additional features such as position of two fingers,
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and width of the touch. Hardware version 3 uses 6 bytes per packet (and
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for 2 fingers the concatenation of two 6 bytes packets) and allows tracking
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of up to 3 fingers. Hardware version 4 uses 6 bytes per packet, and can
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combine a status packet with multiple head or motion packets. Hardware version
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4 allows tracking up to 5 fingers.
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Some Hardware version 3 and version 4 also have a trackpoint which uses a
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separate packet format. It is also 6 bytes per packet.
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The driver tries to support both hardware versions and should be compatible
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with the Xorg Synaptics touchpad driver and its graphical configuration
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utilities.
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Note that a mouse button is also associated with either the touchpad or the
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trackpoint when a trackpoint is available. Disabling the Touchpad in xorg
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(TouchPadOff=0) will also disable the buttons associated with the touchpad.
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Additionally the operation of the touchpad can be altered by adjusting the
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contents of some of its internal registers. These registers are represented
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by the driver as sysfs entries under /sys/bus/serio/drivers/psmouse/serio?
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@ -78,7 +94,7 @@ completeness sake.
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2. Extra knobs
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~~~~~~~~~~~
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Currently the Linux Elantech touchpad driver provides two extra knobs under
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Currently the Linux Elantech touchpad driver provides three extra knobs under
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/sys/bus/serio/drivers/psmouse/serio? for the user.
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* debug
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@ -112,6 +128,20 @@ Currently the Linux Elantech touchpad driver provides two extra knobs under
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data consistency checking can be done. For now checking is disabled by
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default. Currently even turning it on will do nothing.
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* crc_enabled
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Sets crc_enabled to 0/1. The name "crc_enabled" is the official name of
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this integrity check, even though it is not an actual cyclic redundancy
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check.
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Depending on the state of crc_enabled, certain basic data integrity
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verification is done by the driver on hardware version 3 and 4. The
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driver will reject any packet that appears corrupted. Using this knob,
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The state of crc_enabled can be altered with this knob.
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Reading the crc_enabled value will show the active value. Echoing
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"0" or "1" to this file will set the state to "0" or "1".
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/////////////////////////////////////////////////////////////////////////////
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3. Differentiating hardware versions
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@ -746,3 +776,42 @@ byte 5:
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byte 0 ~ 2 for one finger
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byte 3 ~ 5 for another
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8. Trackpoint (for Hardware version 3 and 4)
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=========================================
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8.1 Registers
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~~~~~~~~~
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No special registers have been identified.
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8.2 Native relative mode 6 byte packet format
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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8.2.1 Status Packet
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~~~~~~~~~~~~~
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byte 0:
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bit 7 6 5 4 3 2 1 0
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0 0 sx sy 0 M R L
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byte 1:
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bit 7 6 5 4 3 2 1 0
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~sx 0 0 0 0 0 0 0
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byte 2:
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bit 7 6 5 4 3 2 1 0
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~sy 0 0 0 0 0 0 0
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byte 3:
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bit 7 6 5 4 3 2 1 0
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0 0 ~sy ~sx 0 1 1 0
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byte 4:
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bit 7 6 5 4 3 2 1 0
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x7 x6 x5 x4 x3 x2 x1 x0
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byte 5:
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bit 7 6 5 4 3 2 1 0
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y7 y6 y5 y4 y3 y2 y1 y0
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x and y are written in two's complement spread
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over 9 bits with sx/sy the relative top bit and
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x7..x0 and y7..y0 the lower bits.
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~sx is the inverse of sx, ~sy is the inverse of sy.
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The sign of y is opposite to what the input driver
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expects for a relative movement
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