RE: [PATCH] Input: elantench - Fix the firmware misreport coordinates for trackpoint occasionally.
From: phoenix <hidden>
Date: 2021-09-10 02:18:17
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Hi Dmity, Sorry for late reply.
+ if (packet[4] == 0x80 || packet[5] == 0x80 || + packet[1] >> 7 == packet[4] >> 7 ||
"I think this will reject X coordinates in range [0, 127]. Is this really what is needed? What kind of patterns are you observing when firmware misreports coordinates?" this will reject X in range [128, 256] and [-128, -256]. This patch prevent cursor suddenly jump to screen edge or corner. The patterns we observing as below: 1. x (packet[4]) or y (packet[5]) is 0x80, ex: [xx xx xx xx 80 80] 2. ~x sign bit is same as MSB(most significant bit) of x, ex: [30 00 00 06 00 00] 3. ~y sign bit is same as MSB of y, ex: [30 00 00 06 fa 00] Best regards, Phoenix Huang -----Original Message----- From: Dmitry Torokhov [mailto:dmitry.torokhov@gmail.com] Sent: Tuesday, August 31, 2021 4:24 AM To: phoenix <redacted> Cc: linux-kernel@vger.kernel.org; linux-input@vger.kernel.org; jingle.wu@emc.com.tw; josh.chen@emc.com.tw; dave.wang@emc.com.tw Subject: Re: [PATCH] Input: elantench - Fix the firmware misreport coordinates for trackpoint occasionally. Hi Phoenix, On Mon, Aug 30, 2021 at 08:19:48PM +0800, phoenix wrote:
quoted hunk ↗ jump to hunk
Hi Dmitry, Would you review this patch, thanks Best regards, Phoenix Huang -----Original Message----- From: Phoenix Huang [mailto:phoenix@emc.com.tw] Sent: Thursday, July 29, 2021 9:10 AM To: linux-kernel@vger.kernel.org; linux-input@vger.kernel.org; dmitry.torokhov@gmail.com Cc: jingle.wu@emc.com.tw; josh.chen@emc.com.tw; dave.wang@emc.com.tw; Phoenix Huang [off-list ref] Subject: [PATCH] Input: elantench - Fix the firmware misreport coordinates for trackpoint occasionally. Signed-off-by: Phoenix Huang <redacted> --- drivers/input/mouse/elantech.c | 11 +++++++++++ 1 file changed, 11 insertions(+)diff --git a/drivers/input/mouse/elantech.cb/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(structpsmouse *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 ||
I think this will reject X coordinates in range [0, 127]. Is this really what is needed? What kind of patterns are you observing when firmware misreports coordinates? Thanks. -- Dmitry