1.. _t440_support: 2 3============================================================================== 4Lenovo \*40 series touchpad support 5============================================================================== 6 7The Lenovo \*40 series emulates trackstick buttons on the top part of the 8touchpads. 9 10.. _t440_support_overview: 11 12------------------------------------------------------------------------------ 13Overview 14------------------------------------------------------------------------------ 15 16The Lenovo \*40 series introduced a new type of touchpad. Previously, all 17laptops had a separate set of physical buttons for the 18`trackstick <http://en.wikipedia.org/wiki/Pointing_stick>`_. This 19series removed these buttons, relying on a software emulation of the top 20section of the touchpad. This is visually marked on the trackpad itself, 21and clicks can be triggered by pressing the touchpad down with a finger in 22the respective area: 23 24.. figure:: top-software-buttons.svg 25 :align: center 26 27 Left, right and middle-button click with top software button areas 28 29This page only covers the top software buttons, the bottom button behavior 30is covered in :ref:`Clickpad software buttons <clickpad_softbuttons>`. 31 32Clickpads with a top button area are marked with the 33`INPUT_PROP_TOPBUTTONPAD <https://www.kernel.org/doc/Documentation/input/event-codes.txt>`_ 34property. 35 36.. _t440_support_btn_size: 37 38------------------------------------------------------------------------------ 39Size of the buttons 40------------------------------------------------------------------------------ 41 42The size of the buttons matches the visual markings on this touchpad. 43The width of the left and right buttons is approximately 42% of the 44touchpad's width, the middle button is centered and assigned 16% of the 45touchpad width. 46 47The line of the buttons is 5mm from the top edge of the touchpad, 48measurements of button presses showed that the size of the buttons needs to 49be approximately 10mm high to work reliable (especially when using the 50thumb to press the button). 51 52.. _t440_support_btn_behavior: 53 54------------------------------------------------------------------------------ 55Button behavior 56------------------------------------------------------------------------------ 57 58Movement in the top button area does not generate pointer movement. These 59buttons are not replacement buttons for the bottom button area but have 60their own behavior. Semantically attached to the trackstick device, libinput 61re-routes events from these buttons to appear through the trackstick device. 62 63 64.. graphviz:: 65 66 67 digraph top_button_routing 68 { 69 rankdir="LR"; 70 node [shape="box";] 71 72 trackstick [label="trackstick kernel device"]; 73 touchpad [label="touchpad kernel device"]; 74 75 subgraph cluster0 { 76 bgcolor = floralwhite 77 label = "libinput" 78 79 libinput_ts [label="trackstick libinput_device" 80 style=filled 81 fillcolor=white]; 82 libinput_tp [label="touchpad libinput_device" 83 style=filled 84 fillcolor=white]; 85 86 libinput_tp -> libinput_ts [constraint=false 87 color="red4"]; 88 } 89 90 trackstick -> libinput_ts [arrowhead="none"] 91 touchpad -> libinput_tp [color="red4"] 92 93 events_tp [label="other touchpad events"]; 94 events_topbutton [label="top software button events"]; 95 96 libinput_tp -> events_tp [arrowhead="none"] 97 libinput_ts -> events_topbutton [color="red4"] 98 } 99 100 101 102The top button areas work even if the touchpad is disabled but will be 103disabled when the trackstick device is disabled. If the finger starts inside 104the top area and moves outside the button area the finger is treated as dead 105and must be lifted to generate future buttons. Likewise, movement into the 106top button area does not trigger button events, a click has to start inside 107this area to take effect. 108 109.. _t440_support_identification: 110 111------------------------------------------------------------------------------ 112Kernel support 113------------------------------------------------------------------------------ 114 115The firmware on the first generation of touchpads providing top software 116buttons is buggy and announces wrong ranges. 117`Kernel patches <https://lkml.org/lkml/2014/3/7/722>`_ are required; 118these fixes are available in kernels 3.14.1, 3.15 and later but each 119touchpad needs a separate fix. 120 121The October 2014 refresh of these laptops do not have this firmware bug 122anymore and should work without per-device patches, though 123`this kernel commit <http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=02e07492cdfae9c86e3bd21c0beec88dbcc1e9e8>`_ 124is required. 125 126For a complete list of supported touchpads check 127`the kernel source <http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/input/mouse/synaptics.c>`_ 128(search for "topbuttonpad_pnp_ids"). 129
