linux-kernel - [PATCH 5/6] hid: egalax: Add event filtering

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Message-Id: <1286978302-30034-6-git-send-email-rydberg@euromail.se>
Date:	Wed, 13 Oct 2010 15:58:21 +0200
From:	"Henrik Rydberg" <rydberg@...omail.se>
To:	Jiri Kosina <jkosina@...e.cz>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Philipp Merkel <mail@...lmerk.de>,
	Stephane Chatty <chatty@...c.fr>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, Henrik Rydberg <rydberg@...omail.se>
Subject: [PATCH 5/6] hid: egalax: Add event filtering

Use estimated signal-to-noise ratios to reduce noise and limit the
amount of events emitted.

Signed-off-by: Henrik Rydberg <rydberg@...omail.se>
---
 drivers/hid/hid-egalax.c |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/hid-egalax.c b/drivers/hid/hid-egalax.c
index 2aba897..b21e7dc 100644
--- a/drivers/hid/hid-egalax.c
+++ b/drivers/hid/hid-egalax.c
@@ -27,6 +27,10 @@ MODULE_LICENSE("GPL");
 
 #define MAX_EVENTS		120
 
+/* estimated signal-to-noise ratios */
+#define SN_MOVE			1024
+#define SN_PRESSURE		32
+
 struct egalax_data {
 	__u16 x, y, z;
 	__u8 id;
@@ -59,17 +63,17 @@ static int egalax_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 			field->logical_maximum <<= 3;
 			hid_map_usage(hi, usage, bit, max,
 					EV_ABS, ABS_MT_POSITION_X);
-			set_abs(input, ABS_MT_POSITION_X, field, 0);
+			set_abs(input, ABS_MT_POSITION_X, field, SN_MOVE);
 			/* touchscreen emulation */
-			set_abs(input, ABS_X, field, 0);
+			set_abs(input, ABS_X, field, SN_MOVE);
 			return 1;
 		case HID_GD_Y:
 			field->logical_maximum <<= 3;
 			hid_map_usage(hi, usage, bit, max,
 					EV_ABS, ABS_MT_POSITION_Y);
-			set_abs(input, ABS_MT_POSITION_Y, field, 0);
+			set_abs(input, ABS_MT_POSITION_Y, field, SN_MOVE);
 			/* touchscreen emulation */
-			set_abs(input, ABS_Y, field, 0);
+			set_abs(input, ABS_Y, field, SN_MOVE);
 			return 1;
 		}
 		return 0;
@@ -96,9 +100,9 @@ static int egalax_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 			field->logical_minimum = 0;
 			hid_map_usage(hi, usage, bit, max,
 					EV_ABS, ABS_MT_PRESSURE);
-			set_abs(input, ABS_MT_PRESSURE, field, 0);
+			set_abs(input, ABS_MT_PRESSURE, field, SN_PRESSURE);
 			/* touchscreen emulation */
-			set_abs(input, ABS_PRESSURE, field, 0);
+			set_abs(input, ABS_PRESSURE, field, SN_PRESSURE);
 			return 1;
 		}
 		return 0;
-- 
1.7.1

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