• Dmitry Torokhov's avatar
    Input: psmouse - disable automatic probing of BYD touchpads · e9fb7cc6
    Dmitry Torokhov authored
    BYD automatic protocol detection is extremely unreliable and is often
    triggers false positives on regular mice, Sentelic touchpads, and other
    devices. BYD has several documents that have recommended detection
    sequence, but they conflict with each other and, as far as I can see, still
    would not produce unique enough output to reliably differentiate BYD from
    other PS/2 devices.
    
    OEMs sourcing BYD devices also do not do us any favors by not supplying any
    reasonable DMI data and instead leaving turds like "To Be Filled By O.E.M."
    in place of vendor data, or "System Serial Number" as serial number.
    
    On top of that BYD is not truly modern multitouch controller, but rather a
    single-touch transitional device that only reports absolute coordinates at
    the beginning of finger contact and then reverts to reporting
    displacements, and thus not very precise; the only benefit from using BYD
    mode vs the legacy PS/2 mode is possibility of edge scrolling.
    
    Given the above, and the fact that BYD devices are somewhat uncommon, let's
    disable automatic detection of BYD devices. Users who know they have BYD
    trackpads or want to experiment can attempt to activate BYD protocol via
    sysfs:
    
    	echo -n "byd" > /sys/bus/serio/devices/serio1/drvctl
    
    Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=151691
    Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=175421
    Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=120781
    Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=121281
    Fixes: 98ee3771 ("Input: byd - add BYD PS/2 touchpad driver")
    Cc: stable@vger.kernel.org # 4.6+
    Reviewed-by: default avatarPali Rohár <pali.rohar@gmail.com>
    Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
    e9fb7cc6
psmouse-base.c 48.3 KB