| From be896bd3b72b44126c55768f14c22a8729b0992e Mon Sep 17 00:00:00 2001 |
| From: Phoenix Huang <phoenix@emc.com.tw> |
| Date: Sun, 7 Nov 2021 22:00:03 -0800 |
| Subject: Input: elantench - fix misreporting trackpoint coordinates |
| |
| From: Phoenix Huang <phoenix@emc.com.tw> |
| |
| commit be896bd3b72b44126c55768f14c22a8729b0992e 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> |
| --- |
| drivers/input/mouse/elantech.c | 13 +++++++++++++ |
| 1 file changed, 13 insertions(+) |
| |
| --- a/drivers/input/mouse/elantech.c |
| +++ b/drivers/input/mouse/elantech.c |
| @@ -517,6 +517,19 @@ static void elantech_report_trackpoint(s |
| 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]; |
| |
