mirror of
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7a81ba9cc2
Signed-off-by: Eric Engestrom <eric@engestrom.ch> Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
104 lines
3.9 KiB
Text
104 lines
3.9 KiB
Text
/**
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@page t440_support Lenovo *40 series touchpad support
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The Lenovo *40 series emulates trackstick buttons on the top part of the
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touchpads.
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@section t440_support_overview Overview
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The Lenovo *40 series introduced a new type of touchpad. Previously, all
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laptops had a separate set of physical buttons for the
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<a href="http://en.wikipedia.org/wiki/Pointing_stick">trackstick</a>. This
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series removed these buttons, relying on a software emulation of the top
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section of the touchpad. This is visually marked on the trackpad itself,
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and clicks can be triggered by pressing the touchpad down with a finger in
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the respective area:
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@image html top-software-buttons.svg "Left, right and middle-button click with top software button areas"
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This page only covers the top software buttons, the bottom button behavior
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is covered in @ref clickpad_softbuttons "Clickpad software buttons".
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Clickpads with a top button area are marked with the <a
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href="https://www.kernel.org/doc/Documentation/input/event-codes.txt">INPUT_PROP_TOPBUTTONPAD</a>
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property.
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@section t440_support_btn_size Size of the buttons
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The size of the buttons matches the visual markings on this touchpad.
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The width of the left and right buttons is approximately 42% of the
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touchpad's width, the middle button is centered and assigned 16% of the
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touchpad width.
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The line of the buttons is 5mm from the top edge of the touchpad,
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measurements of button presses showed that the size of the buttons needs to
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be approximately 10mm high to work reliable (especially when using the
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thumb to press the button).
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@section t440_support_btn_behavior Button behavior
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Movement in the top button area does not generate pointer movement. These
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buttons are not replacement buttons for the bottom button area but have
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their own behavior. Semantically attached to the trackstick device, libinput
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re-routes events from these buttons to appear through the trackstick device.
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@dot
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digraph top_button_routing
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{
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rankdir="LR";
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node [shape="box";]
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trackstick [label="trackstick kernel device"];
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touchpad [label="touchpad kernel device"];
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subgraph cluster0 {
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bgcolor = floralwhite
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label = "libinput"
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libinput_ts [label="trackstick libinput_device"
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style=filled
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fillcolor=white];
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libinput_tp [label="touchpad libinput_device"
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style=filled
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fillcolor=white];
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libinput_tp -> libinput_ts [constraint=false
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color="red4"];
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}
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trackstick -> libinput_ts [arrowhead="none"]
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touchpad -> libinput_tp [color="red4"]
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events_tp [label="other touchpad events"];
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events_topbutton [label="top software button events"];
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libinput_tp -> events_tp [arrowhead="none"]
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libinput_ts -> events_topbutton [color="red4"]
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}
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@enddot
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The top button areas work even if the touchpad is disabled but will be
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disabled when the trackstick device is disabled. If the finger starts inside
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the top area and moves outside the button area the finger is treated as dead
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and must be lifted to generate future buttons. Likewise, movement into the
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top button area does not trigger button events, a click has to start inside
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this area to take effect.
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@section t440_support_identification Kernel support
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The firmware on the first generation of touchpads providing top software
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buttons is buggy and announces wrong ranges.
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<a href="https://lkml.org/lkml/2014/3/7/722">Kernel patches</a> are required;
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these fixes are available in kernels 3.14.1, 3.15 and later but each
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touchpad needs a separate fix.
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The October 2014 refresh of these laptops do not have this firmware bug
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anymore and should work without per-device patches, though
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<a href="http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=02e07492cdfae9c86e3bd21c0beec88dbcc1e9e8">this kernel commit</a> is required.
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For a complete list of supported touchpads check <a
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href="http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/input/mouse/synaptics.c">the
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kernel source</a> (search for "topbuttonpad_pnp_ids").
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*/
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