[PATCH] Lower noise cancellation defaults

Simon Thum simon.thum at gmx.de
Thu Nov 24 13:51:20 PST 2011


The noise cancellation was initially adjusted by me to quite old hardware,
lowering the default factor (assumed noise content) from 0.5% to
0.25% may be better on contempoary hardware.

The factor is not just a question of the statistical noise inherent in A/D,
but also of what is worth to actually read from a fingertip. In my tests,
0.25% still allowed for some motion without events being generated, but makes
it hard to take off the finger without  causing additioal motion events.

Signed-off-by: Simon Thum <simon.thum at gmx.de>
---
 src/synaptics.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/synaptics.c b/src/synaptics.c
index 5ca024f..0705b9a 100644
--- a/src/synaptics.c
+++ b/src/synaptics.c
@@ -456,8 +456,8 @@ static void set_default_parameters(InputInfoPtr pInfo)
     accelFactor = 200.0 / diag; /* trial-and-error */
 
     /* hysteresis, assume >= 0 is a detected value (e.g. evdev fuzz) */
-    horizHyst = pars->hyst_x >= 0 ? pars->hyst_x : diag * 0.005;
-    vertHyst = pars->hyst_y >= 0 ? pars->hyst_y : diag * 0.005;
+    horizHyst = pars->hyst_x >= 0 ? pars->hyst_x : diag * 0.0025;
+    vertHyst = pars->hyst_y >= 0 ? pars->hyst_y : diag * 0.0025;
 
     range = priv->maxp - priv->minp + 1;
 
-- 
1.7.3.4


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