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

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Message-ID: <000001d79d99$53762dd0$fa628970$@emc.com.tw>
Date:   Mon, 30 Aug 2021 20:19:48 +0800
From:   "phoenix" <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>
Subject: RE: [PATCH] Input: elantench - Fix the firmware misreport coordinates for trackpoint occasionally.

Hi Dmitry,

Would you review this patch, thanks

Best regards,
Phoenix Huang

-----Original Message-----
From: Phoenix Huang [mailto:phoenix@....com.tw] 
Sent: Thursday, July 29, 2021 9:10 AM
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