linux-kernel - [PATCH] Input: elantench - Fix the firmware misreport coordinates for trackpoint occasionally.

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Date:   Thu, 29 Jul 2021 09:09:40 +0800
From:   Phoenix Huang <phoenix@....com.tw>
To:     linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        dmitry.torokhov@...il.com
Cc:     jingle.wu@....com.tw, josh.chen@....com.tw, dave.wang@....com.tw,
        Phoenix Huang <phoenix@....com.tw>
Subject: [PATCH] Input: elantench - Fix the firmware misreport coordinates for trackpoint occasionally.

Signed-off-by: Phoenix Huang <phoenix@....com.tw>
---
 drivers/input/mouse/elantech.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index 2d0bc029619f..07e1098f2d31 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -517,6 +517,17 @@ static void elantech_report_trackpoint(struct psmouse *psmouse,
 	case 0x16008020U:
 	case 0x26800010U:
 	case 0x36808000U:
+	
+		/* This firmware misreport coordinates for trackpoint occasionally.
+		* So we discard these packets by pattern 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];
 
-- 
2.25.1