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Input: elantench - fix misreporting trackpoint coordinates

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commit be896bd3b7 upstream.

Some firmwares occasionally report bogus data from trackpoint, with X or Y
displacement being too large (outside of [-127, 127] range). Let's drop such
packets so that we do not generate jumps.

Signed-off-by: Phoenix Huang <phoenix@emc.com.tw>
Tested-by: Yufei Du <yufeidu@cs.unc.edu>
Link: https://lore.kernel.org/r/20210729010940.5752-1-phoenix@emc.com.tw
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Phoenix Huang 2021-11-07 22:00:03 -08:00 committed by Greg Kroah-Hartman
parent ce4bec0a54
commit 17ec1c6b45
1 changed files with 13 additions and 0 deletions
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13
drivers/input/mouse/elantech.c
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@ -517,6 +517,19 @@ static void elantech_report_trackpoint(struct psmouse *psmouse,
case 0x16008020U:
case 0x26800010U:
case 0x36808000U:
/*
* This firmware misreport coordinates for trackpoint
* occasionally. Discard packets outside of [-127, 127] range
* to prevent cursor jumps.
*/
if (packet[4] == 0x80 || packet[5] == 0x80 ||
packet[1] >> 7 == packet[4] >> 7 ||
packet[2] >> 7 == packet[5] >> 7) {
elantech_debug("discarding packet [%6ph]\n", packet);
break;
}
x = packet[4] - (int)((packet[1]^0x80) << 1);
y = (int)((packet[2]^0x80) << 1) - packet[5];