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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Peter Hutterer <peter.hutterer@who-t.net>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.14 020/161] Input: synaptics - reset the ABS_X/Y
 fuzz after initializing MT axes
Thread-Topic: [PATCH AUTOSEL for 4.14 020/161] Input: synaptics - reset the
 ABS_X/Y fuzz after initializing MT axes
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Date:   Mon, 9 Apr 2018 00:19:57 +0000
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From: Peter Hutterer <peter.hutterer@who-t.net>

[ Upstream commit 19eb4ed1141bd1096b9bc84ba9c4d03d5830c143 ]

input_mt_init_slots() resets the ABS_X/Y fuzz to 0 and expects the driver
to call input_mt_report_pointer_emulation(). That is based on the MT
position bits which are already defuzzed - hence a fuzz of 0.

In the case of synaptics semi-mt devices, we report the ABS_X/Y axes
manually.  This results in the MT position being defuzzed but the
single-touch emulation missing that defuzzing.

Work around this by re-initializing the ABS_X/Y axes after the MT axis to
get the same fuzz value back.

https://bugs.freedesktop.org/show_bug.cgi?id=3D104533

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/input/mouse/synaptics.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptic=
s.c
index ee5466a374bf..a246fc686bb7 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -1280,6 +1280,16 @@ static void set_input_params(struct psmouse *psmouse=
,
 				    INPUT_MT_POINTER |
 				    (cr48_profile_sensor ?
 					INPUT_MT_TRACK : INPUT_MT_SEMI_MT));
+
+		/*
+		 * For semi-mt devices we send ABS_X/Y ourselves instead of
+		 * input_mt_report_pointer_emulation. But
+		 * input_mt_init_slots() resets the fuzz to 0, leading to a
+		 * filtered ABS_MT_POSITION_X but an unfiltered ABS_X
+		 * position. Let's re-initialize ABS_X/Y here.
+		 */
+		if (!cr48_profile_sensor)
+			set_abs_position_params(dev, &priv->info, ABS_X, ABS_Y);
 	}
=20
 	if (SYN_CAP_PALMDETECT(info->capabilities))
--=20
2.15.1