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    Input: alps - v7: ignore new packets · 8b238115
    Hans de Goede 提交于
    NEW packets are send to indicate a discontinuity in the finger coordinate
    reporting. Specifically a finger may have moved from slot 0 to 1 or vice
    versa.  INPUT_MT_TRACK takes care of this for us.
    
    NEW packets have 3 problems:
    1) They do not contain middle / right button info (on non clickpads)
       this can be worked around by preserving the old button state
    2) They do not contain an accurate fingercount, and they are
       typically send when the number of fingers changes. We cannot use
       the old finger count as that may mismatch with the amount of
       touch coordinates we've available in the NEW packet
    3) Their x data for the second touch is inaccurate leading to
       a possible jump of the x coordinate by 16 units when the first
       non NEW packet comes in
    
    Since problems 2 & 3 cannot be worked around, just ignore them.
    
    BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=86338
    Cc: stable@vger.kernel.org # 3.17
    Signed-off-by: NHans de Goede <hdegoede@redhat.com>
    Tested-by: NBenjamin Tissoires <benjamin.tissoires@redhat.com>
    Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
    8b238115
alps.c 66.5 KB